1
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Bui HT, Wolf C, Wang Y, Haze M, Ardavan A, Heinrich AJ, Phark SH. All-Electrical Driving and Probing of Dressed States in a Single Spin. ACS Nano 2024; 18:12187-12193. [PMID: 38698541 DOI: 10.1021/acsnano.4c00196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2024]
Abstract
The subnanometer distance between tip and sample in a scanning tunneling microscope (STM) enables the application of very large electric fields with a strength as high as ∼1 GV/m. This has allowed for efficient electrical driving of Rabi oscillations of a single spin on a surface at a moderate radiofrequency (RF) voltage on the order of tens of millivolts. Here, we demonstrate the creation of dressed states of a single electron spin localized in the STM tunnel junction by using resonant RF driving voltages. The read-out of these dressed states was achieved all electrically by a weakly coupled probe spin. Our work highlights the strength of the atomic-scale geometry inherent to the STM that facilitates the creation and control of dressed states, which are promising for the design of atomic scale quantum devices using individual spins on surfaces.
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Affiliation(s)
- Hong T Bui
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Korea
- Department of Physics, Ewha Womans University, Seoul 03760, Korea
| | - Christoph Wolf
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Korea
- Ewha Womans University, Seoul 03760, Korea
| | - Yu Wang
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Korea
- Ewha Womans University, Seoul 03760, Korea
| | - Masahiro Haze
- The Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
| | - Arzhang Ardavan
- CAESR, Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, United Kingdom
| | - Andreas J Heinrich
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Korea
- Department of Physics, Ewha Womans University, Seoul 03760, Korea
| | - Soo-Hyon Phark
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Korea
- Ewha Womans University, Seoul 03760, Korea
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2
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Budakian R, Finkler A, Eichler A, Poggio M, Degen CL, Tabatabaei S, Lee I, Hammel PC, Polzik E, Taminiau TH, Walsworth RL, London P, Bleszynski Jayich A, Ajoy A, Pillai A, Wrachtrup J, Jelezko F, Bae Y, Heinrich AJ, Ast CR, Bertet P, Cappellaro P, Bonato C, Altmann Y, Gauger EM. Roadmap on nanoscale magnetic resonance imaging. Nanotechnology 2024. [PMID: 38744268 DOI: 10.1088/1361-6528/ad4b23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
The field of nanoscale magnetic resonance imaging (NanoMRI) was started 30 years ago. It was motivated by the desire to image single molecules and molecular assemblies, such as proteins and virus particles, with near-atomic spatial resolution and on a length scale of 100 nm. Over the years, the NanoMRI field has also expanded to include the goal of useful high-resolution nuclear magnetic resonance (NMR) spectroscopy of molecules under ambient conditions, including samples up to the micron-scale. The realization of these goals requires the development of spin detection techniques that are many orders of magnitude more sensitive than conventional NMR and MRI, capable of detecting and controlling nanoscale ensembles of spins. Over the years, a number of different technical approaches to NanoMRI have emerged, each possessing a distinct set of capabilities for basic and applied areas of science. The goal of this roadmap article is to report the current state of the art in NanoMRI technologies, outline the areas where they are poised to have impact, identify the challenges that lie ahead, and propose methods to meet these challenges. This roadmap also shows how developments in NanoMRI techniques can lead to breakthroughs in emerging quantum science and technology applications.
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Affiliation(s)
- Raffi Budakian
- Department of Physics and Astronomy, University of Waterloo, RAC 1114, Waterloo, N2L 3G1, CANADA
| | - Amit Finkler
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Perlman Building, Room 203A, Rehovot, 7610001, ISRAEL
| | | | - Martino Poggio
- Department of Physics, University of Basel, Klingelbergstrasse 82, Basel, 4001, SWITZERLAND
| | - Christian L Degen
- Department of Physics, Eidgenossiche Technische Hochschule - Zurich, Otto Stern Weg 1, 8093 Zurich, Zurich, 8093, SWITZERLAND
| | - Sahand Tabatabaei
- Department of Physics and Astronomy, University of Waterloo, RAC 2107, Waterloo, N2L 3G1, CANADA
| | - Inhee Lee
- Department of Physics, The Ohio State University, 191 West Woodruff Ave, Columbus, 43210-1132, UNITED STATES
| | - P Chris Hammel
- Department of Physics and Astronomy, University of Waterloo, 191 West Woodruff Ave, Waterloo, N2L 3G1, CANADA
| | - Eugene Polzik
- Niels Bohr Institute, University of Copenhagen, Kobenhavn, 2100, DENMARK
| | - Tim H Taminiau
- Delft University of Technology, Room F033A, Delft, MD, 2600 AA, NETHERLANDS
| | - Ronald L Walsworth
- Quantum Science Center, University of Maryland at College Park, College Park, Maryland, UNITED STATES
| | - Paz London
- University of California Santa Barbara Department of Physics, Department of Physics, University of California, Santa Barbara, California, 93106-9530, UNITED STATES
| | | | - Ashok Ajoy
- E O Lawrence Berkeley National Laboratory, Berkeley, California, 94720-8099, UNITED STATES
| | - Arjun Pillai
- University of California Berkeley Department of Chemistry, University of California, Berkeley, California, 94720-1460, UNITED STATES
| | | | - Fedor Jelezko
- Institut fur Quantenoptik, Universitaet Ulm, Albert-Einstein-Allee 11, 89069, Ulm, GERMANY
| | - Yujeong Bae
- Institute for Basic Science Center for Quantum Nanoscience, Seodaemun-gu, 03760, Korea (the Republic of)
| | - Andreas J Heinrich
- Institute for Basic Science Center for Quantum Nanoscience, Institute for Basic Science, Seodaemun-gu, Seoul, 03760, Korea (the Republic of)
| | - Christian R Ast
- Max-Planck-Institut fuer Festkoerperforschung, D-70506 Stuttgart, GERMANY
| | - Patrice Bertet
- Service de Physique de l'Etat Condense (SPEC), CEA - Saclay, 91191 Gif-sur-Yvette Cedex, Gif-sur-Yvette, FRANCE
| | - Paola Cappellaro
- Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Massachusetts Institute of Technology, MA 02139, USA, Cambridge, Massachusetts, UNITED STATES
| | - Cristian Bonato
- Heriot-Watt University School of Engineering and Physical Sciences, Edinburgh, EH14 4AS, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Yoann Altmann
- Heriot-Watt University, Edinburgh, Edinburgh, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Erik Manuel Gauger
- Institute of Photonics and Quantum Sciences, Heriot-Watt University, School of Engineering and Physical Sciences, Heriot Watt University, Riccarton, Edinburgh, EH14 4AS, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
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3
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Wang Y, Chen Y, Bui HT, Wolf C, Haze M, Mier C, Kim J, Choi DJ, Lutz CP, Bae Y, Phark SH, Heinrich AJ. An atomic-scale multi-qubit platform. Science 2023; 382:87-92. [PMID: 37797000 DOI: 10.1126/science.ade5050] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2022] [Accepted: 08/30/2023] [Indexed: 10/07/2023]
Abstract
Individual electron spins in solids are promising candidates for quantum science and technology, where bottom-up assembly of a quantum device with atomically precise couplings has long been envisioned. Here, we realized atom-by-atom construction, coherent operations, and readout of coupled electron-spin qubits using a scanning tunneling microscope. To enable the coherent control of "remote" qubits that are outside of the tunnel junction, we complemented each electron spin with a local magnetic field gradient from a nearby single-atom magnet. Readout was achieved by using a sensor qubit in the tunnel junction and implementing pulsed double electron spin resonance. Fast single-, two-, and three-qubit operations were thereby demonstrated in an all-electrical fashion. Our angstrom-scale qubit platform may enable quantum functionalities using electron spin arrays built atom by atom on a surface.
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Affiliation(s)
- Yu Wang
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Korea
- Ewha Womans University, Seoul 03760, Korea
| | - Yi Chen
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Korea
- Ewha Womans University, Seoul 03760, Korea
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
| | - Hong T Bui
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Korea
- Department of Physics, Ewha Womans University, Seoul 03760, Korea
| | - Christoph Wolf
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Korea
- Ewha Womans University, Seoul 03760, Korea
| | - Masahiro Haze
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Korea
- The Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
| | - Cristina Mier
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Korea
- Centro de Física de Materiales CFM/MPC (CSIC-UPV/EHU), 20018 Donostia-San Sebastián, Spain
| | - Jinkyung Kim
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Korea
- Department of Physics, Ewha Womans University, Seoul 03760, Korea
| | - Deung-Jang Choi
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Korea
- Centro de Física de Materiales CFM/MPC (CSIC-UPV/EHU), 20018 Donostia-San Sebastián, Spain
- Donostia International Physics Center (DIPC), 20018 Donostia-San Sebastián, Spain
- Ikerbasque, Basque Foundation for Science, 48013 Bilbao, Spain
| | | | - Yujeong Bae
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Korea
- Department of Physics, Ewha Womans University, Seoul 03760, Korea
| | - Soo-Hyon Phark
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Korea
- Ewha Womans University, Seoul 03760, Korea
| | - Andreas J Heinrich
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Korea
- Department of Physics, Ewha Womans University, Seoul 03760, Korea
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4
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Zhang X, Reina-Gálvez J, Wolf C, Wang Y, Aubin H, Heinrich AJ, Choi T. Influence of the Magnetic Tip on Heterodimers in Electron Spin Resonance Combined with Scanning Tunneling Microscopy. ACS Nano 2023; 17:16935-16942. [PMID: 37643247 DOI: 10.1021/acsnano.3c04024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
Investigating the quantum properties of individual spins adsorbed on surfaces by electron spin resonance combined with scanning tunneling microscopy (ESR-STM) has shown great potential for the development of quantum information technology on the atomic scale. A magnetic tip exhibiting high spin polarization is critical for performing an ESR-STM experiment. While the tip has been conventionally treated as providing a static magnetic field in ESR-STM, it was found that the tip can exhibit bistability, influencing ESR spectra. Ideally, the ESR splitting caused by the magnetic interaction between two spins on a surface should be independent of the tip. However, we found that the measured ESR splitting of a metal atom-molecule heterodimer can be tip-dependent. Detailed theoretical analysis reveals that this tip-dependent ESR splitting is caused by a different interaction energy between the tip and each spin of the heterodimer. Our work provides a comprehensive reference for characterizing tip features in ESR-STM experiments and highlights the importance of employing a proper physical model when describing the ESR tip, in particular, for heterospin systems.
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Affiliation(s)
- Xue Zhang
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Republic of Korea
- Ewha Womans University, Seoul 03760, Republic of Korea
- Spin-X Institute, School of Microelectronics, South China University of Technology, Guangzhou 511442, People's Republic of China
| | - Jose Reina-Gálvez
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Republic of Korea
- Ewha Womans University, Seoul 03760, Republic of Korea
| | - Christoph Wolf
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Republic of Korea
- Ewha Womans University, Seoul 03760, Republic of Korea
| | - Yu Wang
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Republic of Korea
- Ewha Womans University, Seoul 03760, Republic of Korea
| | - Hervé Aubin
- Universités Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies, 91120 Palaiseau, France
| | - Andreas J Heinrich
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Republic of Korea
- Department of Physics, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Taeyoung Choi
- Department of Physics, Ewha Womans University, Seoul 03760, Republic of Korea
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5
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Phark S, Bui HT, Ferrón A, Fernández‐Rossier J, Reina‐Gálvez J, Wolf C, Wang Y, Yang K, Heinrich AJ, Lutz CP. Electric-Field-Driven Spin Resonance by On-Surface Exchange Coupling to a Single-Atom Magnet. Adv Sci (Weinh) 2023; 10:e2302033. [PMID: 37466177 PMCID: PMC10520627 DOI: 10.1002/advs.202302033] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 06/11/2023] [Indexed: 07/20/2023]
Abstract
Coherent control of individual atomic and molecular spins on surfaces has recently been demonstrated by using electron spin resonance (ESR) in a scanning tunneling microscope (STM). Here, a combined experimental and modeling study of the ESR of a single hydrogenated Ti atom that is exchange-coupled to a Fe adatom positioned 0.6-0.8 nm away by means of atom manipulation is presented. Continuous wave and pulsed ESR of the Ti spin show a Rabi rate with two contributions, one from the tip and the other from the Fe, whose spin interactions with Ti are modulated by the radio-frequency electric field. The Fe contribution is comparable to the tip, as revealed by its dominance when the tip is retracted, and tunable using a vector magnetic field. The new ESR scheme allows on-surface individual spins to be addressed and coherently controlled without the need for magnetic interaction with a tip. This study establishes a feasible implementation of spin-based multi-qubit systems on surfaces.
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Affiliation(s)
- Soo‐hyon Phark
- Center for Quantum NanoscienceInstitute for Basic Science (IBS)Seoul03760Republic of Korea
- Department of PhysicsEwha Womans UniversitySeoul03760Republic of Korea
- IBM Research DivisionAlmaden Research CenterSan JoseCA95120USA
| | - Hong Thi Bui
- Center for Quantum NanoscienceInstitute for Basic Science (IBS)Seoul03760Republic of Korea
- Department of PhysicsEwha Womans UniversitySeoul03760Republic of Korea
| | - Alejandro Ferrón
- Instituto de Modelado e Innovación Tecnológica (CONICET‐UNNE) and Facultad de Ciencias ExactasNaturales y AgrimensuraUniversidad Nacional del NordesteAvenida Libertad 5400CorrientesW3404AASArgentina
| | | | - Jose Reina‐Gálvez
- Center for Quantum NanoscienceInstitute for Basic Science (IBS)Seoul03760Republic of Korea
- Department of PhysicsEwha Womans UniversitySeoul03760Republic of Korea
| | - Christoph Wolf
- Center for Quantum NanoscienceInstitute for Basic Science (IBS)Seoul03760Republic of Korea
- Department of PhysicsEwha Womans UniversitySeoul03760Republic of Korea
| | - Yu Wang
- Center for Quantum NanoscienceInstitute for Basic Science (IBS)Seoul03760Republic of Korea
- Department of PhysicsEwha Womans UniversitySeoul03760Republic of Korea
| | - Kai Yang
- IBM Research DivisionAlmaden Research CenterSan JoseCA95120USA
- Beijing National Laboratory for Condensed Matter Physics and Institute of PhysicsChinese Academy of SciencesBeijing100864China
| | - Andreas J. Heinrich
- Center for Quantum NanoscienceInstitute for Basic Science (IBS)Seoul03760Republic of Korea
- Department of PhysicsEwha Womans UniversitySeoul03760Republic of Korea
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6
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Phark SH, Chen Y, Bui HT, Wang Y, Haze M, Kim J, Bae Y, Heinrich AJ, Wolf C. Double-Resonance Spectroscopy of Coupled Electron Spins on a Surface. ACS Nano 2023. [PMID: 37406167 DOI: 10.1021/acsnano.3c04754] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/07/2023]
Abstract
Scanning-tunneling microscopy (STM) combined with electron spin resonance (ESR) has enabled single-spin spectroscopy with nanoelectronvolt energy resolution and angstrom-scale spatial resolution, which allows quantum sensing and magnetic resonance imaging at the atomic scale. Extending this spectroscopic tool to a study of multiple spins, however, is nontrivial due to the extreme locality of the STM tunnel junction. Here we demonstrate double electron-electron spin resonance spectroscopy in an STM for two coupled atomic spins by simultaneously and independently driving them using two continuous-wave radio frequency voltages. We show the ability to drive and detect the resonance of a spin that is remote from the tunnel junction while read-out is achieved via the spin in the tunnel junction. Open quantum system simulations for two coupled spins reproduce all double-resonance spectra and further reveal a relaxation time of the remote spin that is longer by an order of magnitude than that of the local spin in the tunnel junction. Our technique can be applied to quantum-coherent multi-spin sensing, simulation, and manipulation in engineered spin structures on surfaces.
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Affiliation(s)
- Soo-Hyon Phark
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Korea
- Ewha Womans University, Seoul 03760, Korea
| | - Yi Chen
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Korea
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China
| | - Hong T Bui
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Korea
- Department of Physics, Ewha Womans University, Seoul 03760, Korea
| | - Yu Wang
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Korea
- Ewha Womans University, Seoul 03760, Korea
| | - Masahiro Haze
- The Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
| | - Jinkyung Kim
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Korea
- Department of Physics, Ewha Womans University, Seoul 03760, Korea
| | - Yujeong Bae
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Korea
- Department of Physics, Ewha Womans University, Seoul 03760, Korea
| | - Andreas J Heinrich
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Korea
- Department of Physics, Ewha Womans University, Seoul 03760, Korea
| | - Christoph Wolf
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Korea
- Ewha Womans University, Seoul 03760, Korea
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7
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Noh K, Colazzo L, Urdaniz C, Lee J, Krylov D, Devi P, Doll A, Heinrich AJ, Wolf C, Donati F, Bae Y. Template-directed 2D nanopatterning of S = 1/2 molecular spins. Nanoscale Horiz 2023; 8:624-631. [PMID: 36752198 DOI: 10.1039/d2nh00375a] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Molecular spins are emerging platforms for quantum information processing. By chemically tuning their molecular structure, it is possible to prepare a robust environment for electron spins and drive the assembly of a large number of qubits in atomically precise spin-architectures. The main challenges in the integration of molecular qubits into solid-state devices are (i) minimizing the interaction with the supporting substrate to suppress quantum decoherence and (ii) controlling the spatial distribution of the spins at the nanometer scale to tailor the coupling among qubits. Herein, we provide a nanofabrication method for the realization of a 2D patterned array of individually addressable Vanadyl Phthalocyanine (VOPc) spin qubits. The molecular nanoarchitecture is crafted on top of a diamagnetic monolayer of Titanyl Phthalocyanine (TiOPc) that electronically decouples the electronic spin of VOPc from the underlying Ag(100) substrate. The isostructural TiOPc interlayer also serves as a template to regulate the spacing between VOPc spin qubits on a scale of a few nanometers, as demonstrated using scanning tunneling microscopy, X-ray circular dichroism, and density functional theory. The long-range molecular ordering is due to a combination of charge transfer from the metallic substrate and strain in the TiOPc interlayer, which is attained without altering the pristine VOPc spin characteristics. Our results pave a viable route towards the future integration of molecular spin qubits into solid-state devices.
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Affiliation(s)
- Kyungju Noh
- Center for Quantum Nanoscience (QNS), Institute of Basic Science (IBS), 03760 Seoul, Republic of Korea.
- Department of Physics, Ewha Womans University, 03760 Seoul, Republic of Korea
| | - Luciano Colazzo
- Center for Quantum Nanoscience (QNS), Institute of Basic Science (IBS), 03760 Seoul, Republic of Korea.
- Ewha Womans University, 03760 Seoul, Republic of Korea
| | - Corina Urdaniz
- Center for Quantum Nanoscience (QNS), Institute of Basic Science (IBS), 03760 Seoul, Republic of Korea.
- Ewha Womans University, 03760 Seoul, Republic of Korea
| | - Jaehyun Lee
- Center for Quantum Nanoscience (QNS), Institute of Basic Science (IBS), 03760 Seoul, Republic of Korea.
- Department of Physics, Ewha Womans University, 03760 Seoul, Republic of Korea
| | - Denis Krylov
- Center for Quantum Nanoscience (QNS), Institute of Basic Science (IBS), 03760 Seoul, Republic of Korea.
- Ewha Womans University, 03760 Seoul, Republic of Korea
| | - Parul Devi
- Center for Quantum Nanoscience (QNS), Institute of Basic Science (IBS), 03760 Seoul, Republic of Korea.
- Ewha Womans University, 03760 Seoul, Republic of Korea
| | - Andrin Doll
- Swiss Light Source (SLS), Paul Scherrer Institut (PSI), 5232 Villigen, Switzerland
| | - Andreas J Heinrich
- Center for Quantum Nanoscience (QNS), Institute of Basic Science (IBS), 03760 Seoul, Republic of Korea.
- Department of Physics, Ewha Womans University, 03760 Seoul, Republic of Korea
| | - Christoph Wolf
- Center for Quantum Nanoscience (QNS), Institute of Basic Science (IBS), 03760 Seoul, Republic of Korea.
- Department of Physics, Ewha Womans University, 03760 Seoul, Republic of Korea
| | - Fabio Donati
- Center for Quantum Nanoscience (QNS), Institute of Basic Science (IBS), 03760 Seoul, Republic of Korea.
- Department of Physics, Ewha Womans University, 03760 Seoul, Republic of Korea
| | - Yujeong Bae
- Center for Quantum Nanoscience (QNS), Institute of Basic Science (IBS), 03760 Seoul, Republic of Korea.
- Department of Physics, Ewha Womans University, 03760 Seoul, Republic of Korea
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8
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Kim J, Noh K, Chen Y, Donati F, Heinrich AJ, Wolf C, Bae Y. Anisotropic Hyperfine Interaction of Surface-Adsorbed Single Atoms. Nano Lett 2022; 22:9766-9772. [PMID: 36317830 PMCID: PMC9756343 DOI: 10.1021/acs.nanolett.2c02782] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 10/20/2022] [Indexed: 06/16/2023]
Abstract
Hyperfine interactions have been widely used in material science, organic chemistry, and structural biology as a sensitive probe to local chemical environments. However, traditional ensemble measurements of hyperfine interactions average over a macroscopic number of spins with different geometrical locations and nuclear isotopes. Here, we use a scanning tunneling microscope (STM) combined with electron spin resonance (ESR) to measure hyperfine spectra of hydrogenated-Ti on MgO/Ag(100) at low-symmetry binding sites and thereby determine the isotropic and anisotropic hyperfine interactions at the single-atom level. Combining vector-field ESR spectroscopy with STM-based atom manipulation, we characterize the full hyperfine tensors of 47Ti and 49Ti and identify significant spatial anisotropy of the hyperfine interactions for both isotopes. Density functional theory calculations reveal that the large hyperfine anisotropy arises from highly anisotropic distributions of the ground-state electron spin density. Our work highlights the power of ESR-STM-enabled single-atom hyperfine spectroscopy in revealing electronic ground states and atomic-scale chemical environments.
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Affiliation(s)
- Jinkyung Kim
- Center
for Quantum Nanoscience (QNS), Institute
for Basic Science (IBS), Seoul 03760, South Korea
- Department
of Physics, Ewha Womans University, Seoul 03760, South Korea
| | - Kyungju Noh
- Center
for Quantum Nanoscience (QNS), Institute
for Basic Science (IBS), Seoul 03760, South Korea
- Department
of Physics, Ewha Womans University, Seoul 03760, South Korea
| | - Yi Chen
- Center
for Quantum Nanoscience (QNS), Institute
for Basic Science (IBS), Seoul 03760, South Korea
- Ewha
Womans University, Seoul 03760, Republic of Korea
| | - Fabio Donati
- Center
for Quantum Nanoscience (QNS), Institute
for Basic Science (IBS), Seoul 03760, South Korea
- Department
of Physics, Ewha Womans University, Seoul 03760, South Korea
| | - Andreas J. Heinrich
- Center
for Quantum Nanoscience (QNS), Institute
for Basic Science (IBS), Seoul 03760, South Korea
- Department
of Physics, Ewha Womans University, Seoul 03760, South Korea
| | - Christoph Wolf
- Center
for Quantum Nanoscience (QNS), Institute
for Basic Science (IBS), Seoul 03760, South Korea
- Ewha
Womans University, Seoul 03760, Republic of Korea
| | - Yujeong Bae
- Center
for Quantum Nanoscience (QNS), Institute
for Basic Science (IBS), Seoul 03760, South Korea
- Department
of Physics, Ewha Womans University, Seoul 03760, South Korea
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9
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Hwang J, Krylov D, Elbertse R, Yoon S, Ahn T, Oh J, Fang L, Jang WJ, Cho FH, Heinrich AJ, Bae Y. Development of a scanning tunneling microscope for variable temperature electron spin resonance. Rev Sci Instrum 2022; 93:093703. [PMID: 36182474 DOI: 10.1063/5.0096081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 08/12/2022] [Indexed: 06/16/2023]
Abstract
Recent advances in improving the spectroscopic energy resolution in scanning tunneling microscopy (STM) have been achieved by integrating electron spin resonance (ESR) with STM. Here, we demonstrate the design and performance of a homebuilt STM capable of ESR at temperatures ranging from 1 to 10 K. The STM is incorporated with a homebuilt Joule-Thomson refrigerator and a two-axis vector magnet. Our STM design allows for the deposition of atoms and molecules directly into the cold STM, eliminating the need to extract the sample for deposition. In addition, we adopt two methods to apply radio-frequency (RF) voltages to the tunnel junction: the early design of wiring to the STM tip directly and a more recent idea to use an RF antenna. Direct comparisons of ESR results measured using the two methods and simulations of electric field distribution around the tunnel junction show that, despite their different designs and capacitive coupling to the tunnel junction, there is no discernible difference in the driving and detection of ESR. Furthermore, at a magnetic field of ∼1.6 T, we observe ESR signals (near 40 GHz) sustained up to 10 K, which is the highest temperature for ESR-STM measurement reported to date, to the best of our knowledge. Although the ESR intensity exponentially decreases with increasing temperature, our ESR-STM system with low noise at the tunnel junction allows us to measure weak ESR signals with intensities of a few fA. Our new design of an ESR-STM system, which is operational in a large frequency and temperature range, can broaden the use of ESR spectroscopy in STM and enable the simple modification of existing STM systems, which will hopefully accelerate a generalized use of ESR-STM.
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Affiliation(s)
- Jiyoon Hwang
- Center for Quantum Nanoscience, Institute for Basic Science, Seoul 03760, South Korea
| | - Denis Krylov
- Center for Quantum Nanoscience, Institute for Basic Science, Seoul 03760, South Korea
| | - Robbie Elbertse
- Department of Quantum Nanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, Delft 2628 CJ, The Netherlands
| | - Sangwon Yoon
- Center for Quantum Nanoscience, Institute for Basic Science, Seoul 03760, South Korea
| | - Taehong Ahn
- Center for Quantum Nanoscience, Institute for Basic Science, Seoul 03760, South Korea
| | - Jeongmin Oh
- Center for Quantum Nanoscience, Institute for Basic Science, Seoul 03760, South Korea
| | - Lei Fang
- Center for Quantum Nanoscience, Institute for Basic Science, Seoul 03760, South Korea
| | - Won-Jun Jang
- Samsung Advanced Institute of Technology, Suwon 13595, South Korea
| | - Franklin H Cho
- Center for Quantum Nanoscience, Institute for Basic Science, Seoul 03760, South Korea
| | - Andreas J Heinrich
- Center for Quantum Nanoscience, Institute for Basic Science, Seoul 03760, South Korea
| | - Yujeong Bae
- Center for Quantum Nanoscience, Institute for Basic Science, Seoul 03760, South Korea
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10
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Abstract
The desire to control and measure individual quantum systems such as atoms and ions in a vacuum has led to significant scientific and engineering developments in the past decades that form the basis of today's quantum information science. Single atoms and molecules on surfaces, on the other hand, are heavily investigated by physicists, chemists, and material scientists in search of novel electronic and magnetic functionalities. These two paths crossed in 2015 when it was first clearly demonstrated that individual spins on a surface can be coherently controlled and read out in an all-electrical fashion. The enabling technique is a combination of scanning tunneling microscopy (STM) and electron spin resonance, which offers unprecedented coherent controllability at the Angstrom length scale. This review aims to illustrate the essential ingredients that allow the quantum operations of single spins on surfaces. Three domains of applications of surface spins, namely quantum sensing, quantum control, and quantum simulation, are discussed with physical principles explained and examples presented. Enabled by the atomically-precise fabrication capability of STM, single spins on surfaces might one day lead to the realization of quantum nanodevices and artificial quantum materials at the atomic scale.
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Affiliation(s)
- Yi Chen
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul, 03760, Korea
- Department of Physics, Ewha Womans University, Seoul, 03760, Korea
| | - Yujeong Bae
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul, 03760, Korea
- Department of Physics, Ewha Womans University, Seoul, 03760, Korea
| | - Andreas J Heinrich
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul, 03760, Korea
- Department of Physics, Ewha Womans University, Seoul, 03760, Korea
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11
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Nguyen LAT, Dhakal KP, Lee Y, Choi W, Nguyen TD, Hong C, Luong DH, Kim YM, Kim J, Lee M, Choi T, Heinrich AJ, Kim JH, Lee D, Duong DL, Lee YH. Spin-Selective Hole-Exciton Coupling in a V-Doped WSe 2 Ferromagnetic Semiconductor at Room Temperature. ACS Nano 2021; 15:20267-20277. [PMID: 34807575 DOI: 10.1021/acsnano.1c08375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
While valley polarization with strong Zeeman splitting is the most prominent characteristic of two-dimensional (2D) transition metal dichalcogenide (TMD) semiconductors under magnetic fields, enhancement of the Zeeman splitting has been demonstrated by incorporating magnetic dopants into the host materials. Unlike Fe, Mn, and Co, V is a distinctive dopant for ferromagnetic semiconducting properties at room temperature with large Zeeman shifting of band edges. Nevertheless, little known is the excitons interacting with spin-polarized carriers in V-doped TMDs. Here, we report anomalous circularly polarized photoluminescence (CPL) in a V-doped WSe2 monolayer at room temperature. Excitons couple to V-induced spin-polarized holes to generate spin-selective positive trions, leading to differences in the populations of neutral excitons and trions between left and right CPL. Using transient absorption spectroscopy, we elucidate the origin of excitons and trions that are inherently distinct for defect-mediated and impurity-mediated trions. Ferromagnetic characteristics are further confirmed by the significant Zeeman splitting of nanodiamonds deposited on the V-doped WSe2 monolayer.
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Affiliation(s)
- Lan-Anh T Nguyen
- Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science (IBS), Suwon 16419, Republic of Korea
- Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Krishna P Dhakal
- Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Yuhan Lee
- Department of Physics, Korea University, Seoul 02841, Republic of Korea
| | - Wooseon Choi
- Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Tuan Dung Nguyen
- Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science (IBS), Suwon 16419, Republic of Korea
- Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Chengyun Hong
- Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science (IBS), Suwon 16419, Republic of Korea
- Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Dinh Hoa Luong
- Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science (IBS), Suwon 16419, Republic of Korea
| | - Young-Min Kim
- Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science (IBS), Suwon 16419, Republic of Korea
- Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Jeongyong Kim
- Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Myeongwon Lee
- Department of Physics, Korea University, Seoul 02841, Republic of Korea
| | - Taeyoung Choi
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Korea
- Department of Physics, Ewha Womans University, Seoul 03760, Korea
| | - Andreas J Heinrich
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Korea
- Department of Physics, Ewha Womans University, Seoul 03760, Korea
| | - Ji-Hee Kim
- Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science (IBS), Suwon 16419, Republic of Korea
- Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Donghun Lee
- Department of Physics, Korea University, Seoul 02841, Republic of Korea
| | - Dinh Loc Duong
- Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science (IBS), Suwon 16419, Republic of Korea
- Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Young Hee Lee
- Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science (IBS), Suwon 16419, Republic of Korea
- Department of Energy Science, Sungkyunkwan University, Suwon 16419, Republic of Korea
- Department of Physics, Sungkyunkwan University, Suwon 16419, Republic of Korea
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12
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Heinrich AJ, Oliver WD, Vandersypen LMK, Ardavan A, Sessoli R, Loss D, Jayich AB, Fernandez-Rossier J, Laucht A, Morello A. Quantum-coherent nanoscience. Nat Nanotechnol 2021; 16:1318-1329. [PMID: 34845333 DOI: 10.1038/s41565-021-00994-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 09/01/2021] [Indexed: 05/25/2023]
Abstract
For the past three decades nanoscience has widely affected many areas in physics, chemistry and engineering, and has led to numerous fundamental discoveries, as well as applications and products. Concurrently, quantum science and technology has developed into a cross-disciplinary research endeavour connecting these same areas and holds burgeoning commercial promise. Although quantum physics dictates the behaviour of nanoscale objects, quantum coherence, which is central to quantum information, communication and sensing, has not played an explicit role in much of nanoscience. This Review describes fundamental principles and practical applications of quantum coherence in nanoscale systems, a research area we call quantum-coherent nanoscience. We structure this Review according to specific degrees of freedom that can be quantum-coherently controlled in a given nanoscale system, such as charge, spin, mechanical motion and photons. We review the current state of the art and focus on outstanding challenges and opportunities unlocked by the merging of nanoscience and coherent quantum operations.
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Affiliation(s)
- Andreas J Heinrich
- Center for Quantum Nanoscience (QNS), Institute for Basic Science, Seoul, Korea.
- Physics Department, Ewha Womans University, Seoul, Korea.
| | - William D Oliver
- Department of Electrical Engineering and Computer Science, and Department of Physics, MIT, Cambridge, MA, USA
- Lincoln Laboratory, MIT, Lexington, MA, USA
| | | | - Arzhang Ardavan
- CAESR, The Clarendon Laboratory, Department of Physics, University of Oxford, Oxford, UK
| | - Roberta Sessoli
- Department of Chemistry 'U. Schiff' & INSTM, University of Florence, Sesto Fiorentino, Italy
| | - Daniel Loss
- Department of Physics, University of Basel, Basel, Switzerland
| | | | - Joaquin Fernandez-Rossier
- QuantaLab, International Iberian Nanotechnology Laboratory (INL), Braga, Portugal
- Departamento de Física Aplicada, Universidad de Alicante, Alicante, Spain
| | - Arne Laucht
- School of Electrical Engineering and Telecommunications, UNSW Sydney, Sydney, New South Wales, Australia
| | - Andrea Morello
- School of Electrical Engineering and Telecommunications, UNSW Sydney, Sydney, New South Wales, Australia.
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13
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Zhang X, Wolf C, Wang Y, Aubin H, Bilgeri T, Willke P, Heinrich AJ, Choi T. Electron spin resonance of single iron phthalocyanine molecules and role of their non-localized spins in magnetic interactions. Nat Chem 2021; 14:59-65. [PMID: 34764471 DOI: 10.1038/s41557-021-00827-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 09/27/2021] [Indexed: 11/09/2022]
Abstract
Electron spin resonance (ESR) spectroscopy is a crucial tool, through spin labelling, in investigations of the chemical structure of materials and of the electronic structure of materials associated with unpaired spins. ESR spectra measured in molecular systems, however, are established on large ensembles of spins and usually require a complicated structural analysis. Recently, the combination of scanning tunnelling microscopy with ESR has proved to be a powerful tool to image and coherently control individual atomic spins on surfaces. Here we extend this technique to single coordination complexes-iron phthalocyanines (FePc)-and investigate the magnetic interactions between their molecular spin with either another molecular spin (in FePc-FePc dimers) or an atomic spin (in FePc-Ti pairs). We show that the molecular spin density of FePc is both localized at the central Fe atom and also distributed to the ligands (Pc), which yields a strongly molecular-geometry-dependent exchange coupling.
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Affiliation(s)
- Xue Zhang
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul, Republic of Korea.,Ewha Womans University, Seoul, Republic of Korea
| | - Christoph Wolf
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul, Republic of Korea.,Ewha Womans University, Seoul, Republic of Korea
| | - Yu Wang
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul, Republic of Korea.,Ewha Womans University, Seoul, Republic of Korea
| | - Hervé Aubin
- Universités Paris-Saclay, CNRS, Centre de Nanosciences et de Nanotechnologies, Palaiseau, France
| | - Tobias Bilgeri
- Institute of Physics, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Philip Willke
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul, Republic of Korea.,Ewha Womans University, Seoul, Republic of Korea.,Physikalisches Institut, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Andreas J Heinrich
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul, Republic of Korea. .,Department of Physics, Ewha Womans University, Seoul, Republic of Korea.
| | - Taeyoung Choi
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul, Republic of Korea. .,Department of Physics, Ewha Womans University, Seoul, Republic of Korea.
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14
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Singha A, Sostina D, Wolf C, Ahmed SL, Krylov D, Colazzo L, Gargiani P, Agrestini S, Noh WS, Park JH, Pivetta M, Rusponi S, Brune H, Heinrich AJ, Barla A, Donati F. Mapping Orbital-Resolved Magnetism in Single Lanthanide Atoms. ACS Nano 2021; 15:16162-16171. [PMID: 34546038 DOI: 10.1021/acsnano.1c05026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Single lanthanide atoms and molecules are promising candidates for atomic data storage and quantum logic due to the long lifetime of their magnetic quantum states. Accessing and controlling these states through electrical transport requires precise knowledge of their electronic configuration at the level of individual atomic orbitals, especially of the outer shells involved in transport. However, no experimental techniques have so far shown the required sensitivity to probe single atoms with orbital selectivity. Here we resolve the magnetism of individual orbitals in Gd and Ho single atoms on MgO/Ag(100) by combining X-ray magnetic circular dichroism with multiplet calculations and density functional theory. In contrast to the usual assumption of bulk-like occupation of the different electronic shells, we establish a charge transfer mechanism leading to an unconventional singly ionized configuration. Our work identifies the role of the valence electrons in determining the quantum level structure and spin-dependent transport properties of lanthanide-based nanomagnets.
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Affiliation(s)
- Aparajita Singha
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Republic of Korea
- Ewha Womans University, Seoul 03760, Republic of Korea
- Max Planck Institute for Solid State Research, Stuttgart 70569, Germany
| | - Daria Sostina
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Republic of Korea
- Ewha Womans University, Seoul 03760, Republic of Korea
| | - Christoph Wolf
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Republic of Korea
- Ewha Womans University, Seoul 03760, Republic of Korea
| | - Safa L Ahmed
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Republic of Korea
- Department of Physics, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Denis Krylov
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Republic of Korea
- Ewha Womans University, Seoul 03760, Republic of Korea
| | - Luciano Colazzo
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Republic of Korea
- Ewha Womans University, Seoul 03760, Republic of Korea
| | - Pierluigi Gargiani
- ALBA Synchrotron Light Source, Cerdanyola del Vallès, 08290 Catalonia, Spain
| | - Stefano Agrestini
- ALBA Synchrotron Light Source, Cerdanyola del Vallès, 08290 Catalonia, Spain
| | - Woo-Suk Noh
- MPPC-CPM, Max Planck POSTECH/Korea Research Initiative, Pohang 37673, Republic of Korea
| | - Jae-Hoon Park
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
| | - Marina Pivetta
- Institute of Physics, École Polytechnique Fédérale de Lausanne, Station 3, CH-1015 Lausanne, Switzerland
| | - Stefano Rusponi
- Institute of Physics, École Polytechnique Fédérale de Lausanne, Station 3, CH-1015 Lausanne, Switzerland
| | - Harald Brune
- Institute of Physics, École Polytechnique Fédérale de Lausanne, Station 3, CH-1015 Lausanne, Switzerland
| | - Andreas J Heinrich
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Republic of Korea
- Department of Physics, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Alessandro Barla
- Istituto di Struttura della Materia (ISM), Consiglio Nazionale delle Ricerche (CNR), I-34149 Trieste, Italy
| | - Fabio Donati
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Republic of Korea
- Department of Physics, Ewha Womans University, Seoul 03760, Republic of Korea
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15
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Singha A, Willke P, Bilgeri T, Zhang X, Brune H, Donati F, Heinrich AJ, Choi T. Engineering atomic-scale magnetic fields by dysprosium single atom magnets. Nat Commun 2021; 12:4179. [PMID: 34234133 PMCID: PMC8263604 DOI: 10.1038/s41467-021-24465-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Accepted: 06/16/2021] [Indexed: 11/08/2022] Open
Abstract
Atomic scale engineering of magnetic fields is a key ingredient for miniaturizing quantum devices and precision control of quantum systems. This requires a unique combination of magnetic stability and spin-manipulation capabilities. Surface-supported single atom magnets offer such possibilities, where long temporal and thermal stability of the magnetic states can be achieved by maximizing the magnet/ic anisotropy energy (MAE) and by minimizing quantum tunnelling of the magnetization. Here, we show that dysprosium (Dy) atoms on magnesium oxide (MgO) have a giant MAE of 250 meV, currently the highest among all surface spins. Using a variety of scanning tunnelling microscopy (STM) techniques including single atom electron spin resonance (ESR), we confirm no spontaneous spin-switching in Dy over days at ≈ 1 K under low and even vanishing magnetic field. We utilize these robust Dy single atom magnets to engineer magnetic nanostructures, demonstrating unique control of magnetic fields with atomic scale tunability.
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Affiliation(s)
- A Singha
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul, Republic of Korea.
- Ewha Womans University, Seoul, Republic of Korea.
- Max Planck Institute for Solid State Research, Stuttgart, Germany.
| | - P Willke
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul, Republic of Korea
- Ewha Womans University, Seoul, Republic of Korea
- Physikalisches Institut, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - T Bilgeri
- Institute of Physics, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - X Zhang
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul, Republic of Korea
- Ewha Womans University, Seoul, Republic of Korea
| | - H Brune
- Institute of Physics, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - F Donati
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul, Republic of Korea
- Department of Physics, Ewha Womans University, Seoul, Republic of Korea
| | - A J Heinrich
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul, Republic of Korea.
- Department of Physics, Ewha Womans University, Seoul, Republic of Korea.
| | - T Choi
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul, Republic of Korea.
- Department of Physics, Ewha Womans University, Seoul, Republic of Korea.
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16
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17
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Jung J, Nam S, Wolf C, Heinrich AJ, Chae J. Atomic-scale intermolecular interaction of hydrogen with a single VOPc molecule on the Au(111) surface. RSC Adv 2021; 11:6240-6245. [PMID: 35423168 PMCID: PMC8694828 DOI: 10.1039/d0ra08951f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 01/26/2021] [Indexed: 12/02/2022] Open
Abstract
Molecular dynamics of hydrogen molecules (H2) on surfaces and their interactions with other molecules have been studied with the goal of improvement of hydrogen storage devices for energy applications. Recently, the dynamic behavior of a H2 at low temperature has been utilized in scanning tunnelling microscopy (STM) for sub-atomic resolution imaging within a single molecule. In this work, we have investigated the intermolecular interaction between H2 and individual vanadyl phthalocyanine (VOPc) molecules on Au(111) substrates by using STM and non-contact atomic force microscopy (NC-AFM). We measured tunnelling spectra and random telegraphic noise (RTN) on VOPc molecules to reveal the origin of the dynamic behavior of the H2. The tunnelling spectra show switching between two states with different tunnelling conductance as a function of sample bias voltage and RTN is measured near transition voltage between the two states. The spatial variation of the RTN indicates that the two-state fluctuation is dependent on the atomic-scale interaction of H2 with the VOPc molecule. Density functional theory calculations show that a H2 molecule can be trapped by a combination of a tip-induced electrostatic potential well and the potential formed by a VOPc underneath. We suggest the origin of the two-state noise as transition of H2 between minima in these potentials with barrier height of 20-30 meV. In addition, the bias dependent AFM images verify that H2 can be trapped and released at the tip-sample junction.
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Affiliation(s)
- Jinoh Jung
- Department of Physics, KAIST Daejeon 34141 Korea
- Center for Quantum Nanoscience, Institute for Basic Science (IBS) Seoul 03760 Korea
| | - Shinjae Nam
- Center for Quantum Nanoscience, Institute for Basic Science (IBS) Seoul 03760 Korea
- Physics Department, Ewha Womans University Seoul 03760 Korea
| | - Christoph Wolf
- Center for Quantum Nanoscience, Institute for Basic Science (IBS) Seoul 03760 Korea
- Ewha Womans University Seoul 03760 Korea
| | - Andreas J Heinrich
- Center for Quantum Nanoscience, Institute for Basic Science (IBS) Seoul 03760 Korea
- Physics Department, Ewha Womans University Seoul 03760 Korea
| | - Jungseok Chae
- Center for Quantum Nanoscience, Institute for Basic Science (IBS) Seoul 03760 Korea
- Ewha Womans University Seoul 03760 Korea
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18
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Zhang X, Willke P, Singha A, Wolf C, Esat T, Choi M, Heinrich AJ, Choi T. Probing Magnetism in Artificial Metal-Organic Complexes Using Electronic Spin Relaxometry. J Phys Chem Lett 2020; 11:5618-5624. [PMID: 32578990 DOI: 10.1021/acs.jpclett.0c01281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Single spins are considered as a versatile candidate for miniaturizing information devices down to the nanoscale. To engineer the spin's properties, metal-organic frameworks provide a promising route which in turn requires thorough understanding of the metal-molecule interaction. Here, we investigate the magnetic robustness of a single iron (Fe) atom in artificially built Fe-tetracyanoethylene (TCNE) complexes by using low-temperature scanning tunneling microscopy (STM). We find that the magnetic anisotropy and spin relaxation dynamics of the Fe atom within the complexes remain unperturbed in comparison to well-isolated Fe atoms. Density functional theory (DFT) calculations support our experimental findings, suggesting that the 3d orbitals of the Fe atom remain largely undisturbed while the 4s and 4p orbitals are rearranged in the process of forming a complex. To precisely determine the location of the spin center within the complex, we utilize STM-based spin relaxometry, mapping out the spatial dependence of spin relaxation with subnanometer resolution. Our work suggests that the magnetic properties of atoms can remain unchanged while being embedded in a weakly bound molecular framework.
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Affiliation(s)
- Xue Zhang
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Republic of Korea
- Ewha Womans University, Seoul 03760, Republic of Korea
| | - Philip Willke
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Republic of Korea
- Ewha Womans University, Seoul 03760, Republic of Korea
| | - Aparajita Singha
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Republic of Korea
- Ewha Womans University, Seoul 03760, Republic of Korea
| | - Christoph Wolf
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Republic of Korea
- Ewha Womans University, Seoul 03760, Republic of Korea
| | - Taner Esat
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Republic of Korea
- Ewha Womans University, Seoul 03760, Republic of Korea
| | - Minhee Choi
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Republic of Korea
- Department of Physics, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Andreas J Heinrich
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Republic of Korea
- Department of Physics, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Taeyoung Choi
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Republic of Korea
- Department of Physics, Ewha Womans University, Seoul 03760, Republic of Korea
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19
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Ternes M, Lutz CP, Heinrich AJ, Schneider WD. Sensing the Spin of an Individual Ce Adatom. Phys Rev Lett 2020; 124:167202. [PMID: 32383899 DOI: 10.1103/physrevlett.124.167202] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Accepted: 04/01/2020] [Indexed: 06/11/2023]
Abstract
The magnetic moment of rare earth elements originates from electrons in the partially filled 4f orbitals. Accessing this moment electrically by scanning tunneling spectroscopy is hampered by shielding of outerlying orbitals. Here, we show that we can detect the magnetic moment of an individual Ce atom adsorbed on a Cu_{2}N ultrathin film on Cu(100) by using a sensor tip that has its apex functionalized with a Kondo screened spin system. We calibrate the sensor tip by deliberately coupling it to a well characterized Fe atom. Subsequently, we use the splitting of the tip's Kondo resonance when approaching a spectroscopically dark Ce atom to sense its magnetic moment.
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Affiliation(s)
- Markus Ternes
- RWTH Aachen University, Institute of Physics, D-52074 Aachen, Germany
- Peter-Grünberg-Institute, Forschungszentrum Jülich, D-52425 Jülich, Germany
| | | | - Andreas J Heinrich
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Republic of Korea
- Physics Department, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Wolf-Dieter Schneider
- Ecole Polytechnique Fédérale de Lausanne (EPFL), Institut de Physique, CH-1015 Lausanne, Switzerland
- Fritz-Haber-Institute of the Max-Planck-Society, Faradayweg 4-6, D-14195 Berlin, Germany
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Willke P, Singha A, Zhang X, Esat T, Lutz CP, Heinrich AJ, Choi T. Tuning Single-Atom Electron Spin Resonance in a Vector Magnetic Field. Nano Lett 2019; 19:8201-8206. [PMID: 31661282 DOI: 10.1021/acs.nanolett.9b03559] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Spin resonance of single spin centers bears great potential for chemical structure analysis, quantum sensing, and quantum coherent manipulation. Essential for these experiments is the presence of a two-level spin system whose energy splitting can be chosen by applying a magnetic field. In recent years, a combination of electron spin resonance (ESR) and scanning tunneling microscopy (STM) has been demonstrated as a technique to detect magnetic properties of single atoms on surfaces and to achieve sub-microelectronvolts energy resolution. Nevertheless, up to now the role of the required magnetic fields has not been elucidated. Here, we perform single-atom ESR on individual Fe atoms adsorbed on magnesium oxide (MgO) using a two-dimensional vector magnetic field as well as the local field of the magnetic STM tip in a commercially available STM. We show how the ESR amplitude can be greatly improved by optimizing the magnetic fields, revealing in particular an enhanced signal at large in-plane magnetic fields. Moreover, we demonstrate that the stray field from the magnetic STM tip is a versatile tool. We use it here to drive the electron spin more efficiently and to perform ESR measurements at constant frequency by employing tip-field sweeps. Lastly, we show that it is possible to perform ESR using only the tip field, under zero external magnetic field, which promises to make this technique available in many existing STM systems.
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Affiliation(s)
- Philip Willke
- Center for Quantum Nanoscience , Institute for Basic Science (IBS) , Seoul 03760 , Republic of Korea
- Ewha Womans University , Seoul 03760 , Republic of Korea
| | - Aparajita Singha
- Center for Quantum Nanoscience , Institute for Basic Science (IBS) , Seoul 03760 , Republic of Korea
- Ewha Womans University , Seoul 03760 , Republic of Korea
| | - Xue Zhang
- Center for Quantum Nanoscience , Institute for Basic Science (IBS) , Seoul 03760 , Republic of Korea
- Ewha Womans University , Seoul 03760 , Republic of Korea
| | - Taner Esat
- Center for Quantum Nanoscience , Institute for Basic Science (IBS) , Seoul 03760 , Republic of Korea
- Ewha Womans University , Seoul 03760 , Republic of Korea
| | | | - Andreas J Heinrich
- Center for Quantum Nanoscience , Institute for Basic Science (IBS) , Seoul 03760 , Republic of Korea
- Department of Physics , Ewha Womans University , Seoul 03760 , Republic of Korea
| | - Taeyoung Choi
- Center for Quantum Nanoscience , Institute for Basic Science (IBS) , Seoul 03760 , Republic of Korea
- Department of Physics , Ewha Womans University , Seoul 03760 , Republic of Korea
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21
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Yang K, Paul W, Phark SH, Willke P, Bae Y, Choi T, Esat T, Ardavan A, Heinrich AJ, Lutz CP. Coherent spin manipulation of individual atoms on a surface. Science 2019; 366:509-512. [DOI: 10.1126/science.aay6779] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 10/01/2019] [Indexed: 11/03/2022]
Affiliation(s)
- Kai Yang
- IBM Almaden Research Center, San Jose, CA 95120, USA
| | - William Paul
- IBM Almaden Research Center, San Jose, CA 95120, USA
| | - Soo-Hyon Phark
- IBM Almaden Research Center, San Jose, CA 95120, USA
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Republic of Korea
- Department of Physics, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Philip Willke
- IBM Almaden Research Center, San Jose, CA 95120, USA
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Republic of Korea
- Ewha Womans University, Seoul 03760, Republic of Korea
| | - Yujeong Bae
- IBM Almaden Research Center, San Jose, CA 95120, USA
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Republic of Korea
- Ewha Womans University, Seoul 03760, Republic of Korea
| | - Taeyoung Choi
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Republic of Korea
- Department of Physics, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Taner Esat
- IBM Almaden Research Center, San Jose, CA 95120, USA
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Republic of Korea
- Ewha Womans University, Seoul 03760, Republic of Korea
| | - Arzhang Ardavan
- CAESR, Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK
| | - Andreas J. Heinrich
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Republic of Korea
- Department of Physics, Ewha Womans University, Seoul 03760, Republic of Korea
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22
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Yang K, Paul W, Natterer FD, Lado JL, Bae Y, Willke P, Choi T, Ferrón A, Fernández-Rossier J, Heinrich AJ, Lutz CP. Tuning the Exchange Bias on a Single Atom from 1 mT to 10 T. Phys Rev Lett 2019; 122:227203. [PMID: 31283288 DOI: 10.1103/physrevlett.122.227203] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Indexed: 06/09/2023]
Abstract
Shrinking spintronic devices to the nanoscale ultimately requires localized control of individual atomic magnetic moments. At these length scales, the exchange interaction plays important roles, such as in the stabilization of spin-quantization axes, the production of spin frustration, and creation of magnetic ordering. Here, we demonstrate the precise control of the exchange bias experienced by a single atom on a surface, covering an energy range of 4 orders of magnitude. The exchange interaction is continuously tunable from milli-eV to micro-eV by adjusting the separation between a spin-1/2 atom on a surface and the magnetic tip of a scanning tunneling microscope. We seamlessly combine inelastic electron tunneling spectroscopy and electron spin resonance to map out the different energy scales. This control of exchange bias over a wide span of energies provides versatile control of spin states, with applications ranging from precise tuning of quantum state properties, to strong exchange bias for local spin doping. In addition, we show that a time-varying exchange interaction generates a localized ac magnetic field that resonantly drives the surface spin. The static and dynamic control of the exchange interaction at the atomic scale provides a new tool to tune the quantum states of coupled-spin systems.
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Affiliation(s)
- Kai Yang
- IBM Almaden Research Center, San Jose, California 95120, USA
| | - William Paul
- IBM Almaden Research Center, San Jose, California 95120, USA
| | - Fabian D Natterer
- IBM Almaden Research Center, San Jose, California 95120, USA
- Physik-Institut, University of Zurich, CH-8057 Zurich, Switzerland
| | - Jose L Lado
- Institute for Theoretical Physics, ETH Zurich, 8093 Zurich, Switzerland
| | - Yujeong Bae
- IBM Almaden Research Center, San Jose, California 95120, USA
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Republic of Korea
- Department of Physics, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Philip Willke
- IBM Almaden Research Center, San Jose, California 95120, USA
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Republic of Korea
- Department of Physics, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Taeyoung Choi
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Republic of Korea
- Department of Physics, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Alejandro Ferrón
- Instituto de Modelado e Innovación Tecnológica (CONICET-UNNE), and Facultad de Ciencias Exactas, Naturales y Agrimensura, Universidad Nacional del Nordeste, Avenida Libertad 5400, W3404AAS Corrientes, Argentina
| | - Joaquín Fernández-Rossier
- QuantaLab, International Iberian Nanotechnology Laboratory (INL), Avenida Mestre José Veiga, 4715-310 Braga, Portugal
- Departamento de Física Aplicada, Universidad de Alicante, San Vicente del Raspeig 03690, Spain
| | - Andreas J Heinrich
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Republic of Korea
- Department of Physics, Ewha Womans University, Seoul 03760, Republic of Korea
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Yang K, Willke P, Bae Y, Ferrón A, Lado JL, Ardavan A, Fernández-Rossier J, Heinrich AJ, Lutz CP. Electrically controlled nuclear polarization of individual atoms. Nat Nanotechnol 2018; 13:1120-1125. [PMID: 30397285 DOI: 10.1038/s41565-018-0296-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 10/02/2018] [Indexed: 06/08/2023]
Abstract
Nuclear spins serve as sensitive probes in chemistry1 and materials science2 and are promising candidates for quantum information processing3-6. NMR, the resonant control of nuclear spins, is a powerful tool for probing local magnetic environments in condensed matter systems, which range from magnetic ordering in high-temperature superconductors7,8 and spin liquids9 to quantum magnetism in nanomagnets10,11. Increasing the sensitivity of NMR to the single-atom scale is challenging as it requires a strong polarization of nuclear spins, well in excess of the low polarizations obtained at thermal equilibrium, as well as driving and detecting them individually4,5,12. Strong nuclear spin polarization, known as hyperpolarization, can be achieved through hyperfine coupling with electron spins2. The fundamental mechanism is the conservation of angular momentum: an electron spin flips and a nuclear spin flops. The nuclear hyperpolarization enables applications such as in vivo magnetic resonance imaging using nanoparticles13, and is harnessed for spin-based quantum information processing in quantum dots14 and doped silicon15-17. Here we polarize the nuclear spins of individual copper atoms on a surface using a spin-polarized current in a scanning tunnelling microscope. By employing the electron-nuclear flip-flop hyperfine interaction, the spin angular momentum is transferred from tunnelling electrons to the nucleus of individual Cu atoms. The direction and magnitude of the nuclear polarization is controlled by the direction and amplitude of the current. The nuclear polarization permits the detection of the NMR of individual Cu atoms, which is used to sense the local magnetic environment of the Cu electron spin.
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Affiliation(s)
- Kai Yang
- IBM Almaden Research Center, San Jose, CA, USA
| | - Philip Willke
- IBM Almaden Research Center, San Jose, CA, USA
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul, Republic of Korea
- Department of Physics, Ewha Womans University, Seoul, Republic of Korea
| | - Yujeong Bae
- IBM Almaden Research Center, San Jose, CA, USA
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul, Republic of Korea
- Department of Physics, Ewha Womans University, Seoul, Republic of Korea
| | - Alejandro Ferrón
- Instituto de Modelado e Innovación Tecnológica (CONICET-UNNE) and Facultad de Ciencias Exactas, Naturales y Agrimensura, Universidad Nacional del Nordeste, Corrientes, Argentina
| | - Jose L Lado
- QuantaLab, International Iberian Nanotechnology Laboratory (INL), Braga, Portugal
- Institute for Theoretical Physics, ETH Zurich, Zurich, Switzerland
| | - Arzhang Ardavan
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford, UK
| | - Joaquín Fernández-Rossier
- QuantaLab, International Iberian Nanotechnology Laboratory (INL), Braga, Portugal
- Departamento de Física Aplicada, Universidad de Alicante, San Vicente del Raspeig, Spain
| | - Andreas J Heinrich
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul, Republic of Korea.
- Department of Physics, Ewha Womans University, Seoul, Republic of Korea.
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Willke P, Bae Y, Yang K, Lado JL, Ferrón A, Choi T, Ardavan A, Fernández-Rossier J, Heinrich AJ, Lutz CP. Hyperfine interaction of individual atoms on a surface. Science 2018; 362:336-339. [DOI: 10.1126/science.aat7047] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Accepted: 08/15/2018] [Indexed: 11/02/2022]
Affiliation(s)
- Philip Willke
- IBM Almaden Research Center, San Jose, CA 95120, USA
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Republic of Korea
- Department of Physics, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Yujeong Bae
- IBM Almaden Research Center, San Jose, CA 95120, USA
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Republic of Korea
- Department of Physics, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Kai Yang
- IBM Almaden Research Center, San Jose, CA 95120, USA
| | - Jose L. Lado
- QuantaLab, International Iberian Nanotechnology Laboratory (INL), 4715-310 Braga, Portugal
- Institute for Theoretical Physics, ETH Zurich, 8093 Zurich, Switzerland
| | - Alejandro Ferrón
- Instituto de Modelado e Innovación Tecnológica (CONICET-UNNE), Facultad de Ciencias Exactas, Naturales y Agrimensura, Universidad Nacional del Nordeste, W3404AAS Corrientes, Argentina
| | - Taeyoung Choi
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Republic of Korea
- Department of Physics, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Arzhang Ardavan
- Centre for Advanced Electron Spin Resonance, Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK
| | | | - Andreas J. Heinrich
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Republic of Korea
- Department of Physics, Ewha Womans University, Seoul 03760, Republic of Korea
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25
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Willke P, Paul W, Natterer FD, Yang K, Bae Y, Choi T, Fernández-Rossier J, Heinrich AJ, Lutz CP. Probing quantum coherence in single-atom electron spin resonance. Sci Adv 2018; 4:eaaq1543. [PMID: 29464211 PMCID: PMC5815865 DOI: 10.1126/sciadv.aaq1543] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2017] [Accepted: 01/16/2018] [Indexed: 05/24/2023]
Abstract
Spin resonance of individual spin centers allows applications ranging from quantum information technology to atomic-scale magnetometry. To protect the quantum properties of a spin, control over its local environment, including energy relaxation and decoherence processes, is crucial. However, in most existing architectures, the environment remains fixed by the crystal structure and electrical contacts. Recently, spin-polarized scanning tunneling microscopy (STM), in combination with electron spin resonance (ESR), allowed the study of single adatoms and inter-atomic coupling with an unprecedented combination of spatial and energy resolution. We elucidate and control the interplay of an Fe single spin with its atomic-scale environment by precisely tuning the phase coherence time T2 using the STM tip as a variable electrode. We find that the decoherence rate is the sum of two main contributions. The first scales linearly with tunnel current and shows that, on average, every tunneling electron causes one dephasing event. The second, effective even without current, arises from thermally activated spin-flip processes of tip spins. Understanding these interactions allows us to maximize T2 and improve the energy resolution. It also allows us to maximize the amplitude of the ESR signal, which supports measurements even at elevated temperatures as high as 4 K. Thus, ESR-STM allows control of quantum coherence in individual, electrically accessible spins.
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Affiliation(s)
- Philip Willke
- Center for Quantum Nanoscience, Institute for Basic Science, Seoul 03760, Republic of Korea
- IBM Almaden Research Center, San Jose, CA 95120, USA
- Department of Physics, Ewha Womans University, Seoul 03760, Republic of Korea
- IV. Physical Institute, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - William Paul
- IBM Almaden Research Center, San Jose, CA 95120, USA
| | - Fabian D. Natterer
- IBM Almaden Research Center, San Jose, CA 95120, USA
- Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Kai Yang
- IBM Almaden Research Center, San Jose, CA 95120, USA
| | - Yujeong Bae
- Center for Quantum Nanoscience, Institute for Basic Science, Seoul 03760, Republic of Korea
- IBM Almaden Research Center, San Jose, CA 95120, USA
- Department of Physics, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Taeyoung Choi
- Center for Quantum Nanoscience, Institute for Basic Science, Seoul 03760, Republic of Korea
- Department of Physics, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Joaquin Fernández-Rossier
- QuantaLab, International Iberian Nanotechnology Laboratory, Avenida Mestre José Veiga, 4715-310 Braga, Portugal
| | - Andreas J. Heinrich
- Center for Quantum Nanoscience, Institute for Basic Science, Seoul 03760, Republic of Korea
- Department of Physics, Ewha Womans University, Seoul 03760, Republic of Korea
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26
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Yang K, Bae Y, Paul W, Natterer FD, Willke P, Lado JL, Ferrón A, Choi T, Fernández-Rossier J, Heinrich AJ, Lutz CP. Engineering the Eigenstates of Coupled Spin-1/2 Atoms on a Surface. Phys Rev Lett 2017; 119:227206. [PMID: 29286811 DOI: 10.1103/physrevlett.119.227206] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Indexed: 06/07/2023]
Abstract
Quantum spin networks having engineered geometries and interactions are eagerly pursued for quantum simulation and access to emergent quantum phenomena such as spin liquids. Spin-1/2 centers are particularly desirable, because they readily manifest coherent quantum fluctuations. Here we introduce a controllable spin-1/2 architecture consisting of titanium atoms on a magnesium oxide surface. We tailor the spin interactions by atomic-precision positioning using a scanning tunneling microscope (STM) and subsequently perform electron spin resonance on individual atoms to drive transitions into and out of quantum eigenstates of the coupled-spin system. Interactions between the atoms are mapped over a range of distances extending from highly anisotropic dipole coupling to strong exchange coupling. The local magnetic field of the magnetic STM tip serves to precisely tune the superposition states of a pair of spins. The precise control of the spin-spin interactions and ability to probe the states of the coupled-spin network by addressing individual spins will enable the exploration of quantum many-body systems based on networks of spin-1/2 atoms on surfaces.
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Affiliation(s)
- Kai Yang
- IBM Almaden Research Center, San Jose, California 95120, USA
| | - Yujeong Bae
- IBM Almaden Research Center, San Jose, California 95120, USA
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Republic of Korea
- Department of Physics, Ewha Womans University, Seoul 03760, Republic of Korea
| | - William Paul
- IBM Almaden Research Center, San Jose, California 95120, USA
| | - Fabian D Natterer
- IBM Almaden Research Center, San Jose, California 95120, USA
- Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Philip Willke
- IBM Almaden Research Center, San Jose, California 95120, USA
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Republic of Korea
- Department of Physics, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Jose L Lado
- QuantaLab, International Iberian Nanotechnology Laboratory (INL), Avenida Mestre José Veiga, 4715-310 Braga, Portugal
| | - Alejandro Ferrón
- Instituto de Modelado e Innovación Tecnológica (CONICET-UNNE), and Facultad de Ciencias Exactas, Naturales y Agrimensura, Universidad Nacional del Nordeste, Avenida Libertad 5400, W3404AAS Corrientes, Argentina
| | - Taeyoung Choi
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Republic of Korea
- Department of Physics, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Joaquín Fernández-Rossier
- QuantaLab, International Iberian Nanotechnology Laboratory (INL), Avenida Mestre José Veiga, 4715-310 Braga, Portugal
- Departamento de Física Aplicada, Universidad de Alicante, San Vicente del Raspeig 03690, Spain
| | - Andreas J Heinrich
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Republic of Korea
- Department of Physics, Ewha Womans University, Seoul 03760, Republic of Korea
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27
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Choi S, Choi HJ, Ok JM, Lee Y, Jang WJ, Lee AT, Kuk Y, Lee S, Heinrich AJ, Cheong SW, Bang Y, Johnston S, Kim JS, Lee J. Switching Magnetism and Superconductivity with Spin-Polarized Current in Iron-Based Superconductor. Phys Rev Lett 2017; 119:227001. [PMID: 29286823 DOI: 10.1103/physrevlett.119.227001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Indexed: 06/07/2023]
Abstract
We explore a new mechanism for switching magnetism and superconductivity in a magnetically frustrated iron-based superconductor using spin-polarized scanning tunneling microscopy (SPSTM). Our SPSTM study on single-crystal Sr_{2}VO_{3}FeAs shows that a spin-polarized tunneling current can switch the Fe-layer magnetism into a nontrivial C_{4} (2×2) order, which cannot be achieved by thermal excitation with an unpolarized current. Our tunneling spectroscopy study shows that the induced C_{4} (2×2) order has characteristics of plaquette antiferromagnetic order in the Fe layer and strongly suppresses superconductivity. Also, thermal agitation beyond the bulk Fe spin ordering temperature erases the C_{4} state. These results suggest a new possibility of switching local superconductivity by changing the symmetry of magnetic order with spin-polarized and unpolarized tunneling currents in iron-based superconductors.
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Affiliation(s)
- Seokhwan Choi
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
| | - Hyoung Joon Choi
- Department of Physics and Center for Computational Studies of Advanced Electronic Material Properties, Yonsei University, Seoul 03722, Korea
| | - Jong Mok Ok
- Department of Physics, Pohang University of Science and Technology, Pohang 37673, Korea
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science, Pohang 37673, Korea
| | - Yeonghoon Lee
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
| | - Won-Jun Jang
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
- Center for Axion and Precision Physics Research, Institute for Basic Science (IBS), Daejeon 34051, Korea
| | - Alex Taekyung Lee
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, USA
| | - Young Kuk
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Korea
| | - SungBin Lee
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
| | - Andreas J Heinrich
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Korea
- Physics Department, Ewha Womans University, Seoul 03760, Korea
| | - Sang-Wook Cheong
- Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
| | - Yunkyu Bang
- Department of Physics, Chonnam National University, Gwangju 61186, Korea
| | - Steven Johnston
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996-1200, USA
| | - Jun Sung Kim
- Department of Physics, Pohang University of Science and Technology, Pohang 37673, Korea
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science, Pohang 37673, Korea
| | - Jhinhwan Lee
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
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28
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Choi T, Paul W, Rolf-Pissarczyk S, Macdonald AJ, Natterer FD, Yang K, Willke P, Lutz CP, Heinrich AJ. Atomic-scale sensing of the magnetic dipolar field from single atoms. Nat Nanotechnol 2017; 12:420-424. [PMID: 28263962 DOI: 10.1038/nnano.2017.18] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 01/26/2017] [Indexed: 06/06/2023]
Abstract
Spin resonance provides the high-energy resolution needed to determine biological and material structures by sensing weak magnetic interactions. In recent years, there have been notable achievements in detecting and coherently controlling individual atomic-scale spin centres for sensitive local magnetometry. However, positioning the spin sensor and characterizing spin-spin interactions with sub-nanometre precision have remained outstanding challenges. Here, we use individual Fe atoms as an electron spin resonance (ESR) sensor in a scanning tunnelling microscope to measure the magnetic field emanating from nearby spins with atomic-scale precision. On artificially built assemblies of magnetic atoms (Fe and Co) on a magnesium oxide surface, we measure that the interaction energy between the ESR sensor and an adatom shows an inverse-cube distance dependence (r-3.01±0.04). This demonstrates that the atoms are predominantly coupled by the magnetic dipole-dipole interaction, which, according to our observations, dominates for atom separations greater than 1 nm. This dipolar sensor can determine the magnetic moments of individual adatoms with high accuracy. The achieved atomic-scale spatial resolution in remote sensing of spins may ultimately allow the structural imaging of individual magnetic molecules, nanostructures and spin-labelled biomolecules.
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Affiliation(s)
- Taeyoung Choi
- IBM Almaden Research Center, San Jose, California 95120, USA
| | - William Paul
- IBM Almaden Research Center, San Jose, California 95120, USA
| | - Steffen Rolf-Pissarczyk
- Max Planck Institute for the Structure and Dynamics of Matter, Hamburg 22761, Germany
- Max Planck Institute for Solid State Research, Stuttgart 70569, Germany
| | - Andrew J Macdonald
- University of British Columbia &Quantum Matter Institute, Vancouver, BC V6T 1Z4, Canada
| | - Fabian D Natterer
- IBM Almaden Research Center, San Jose, California 95120, USA
- Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Kai Yang
- IBM Almaden Research Center, San Jose, California 95120, USA
- School of Physical Sciences and Key Laboratory of Vacuum Physics, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Philip Willke
- IBM Almaden Research Center, San Jose, California 95120, USA
- IV. Physical Institute, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | | | - Andreas J Heinrich
- Center for Quantum Nanoscience, Institute for Basic Science (IBS), Seoul 03760, Republic of Korea
- Physics Department, Ewha Womans University, Seoul, Republic of Korea
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Paul W, Baumann S, Lutz CP, Heinrich AJ. Generation of constant-amplitude radio-frequency sweeps at a tunnel junction for spin resonance STM. Rev Sci Instrum 2016; 87:074703. [PMID: 27475577 DOI: 10.1063/1.4955446] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2015] [Accepted: 06/26/2016] [Indexed: 06/06/2023]
Abstract
We describe the measurement and successful compensation of the radio-frequency transfer function of a scanning tunneling microscope over a wide frequency range (15.5-35.5 GHz) and with high dynamic range (>50 dB). The precise compensation of cabling resonances and attenuations is critical for the production of constant-voltage frequency sweeps for electric-field driven electron spin resonance (ESR) experiments. We also demonstrate that a well-calibrated tunnel junction voltage is necessary to avoid spurious ESR peaks that can arise due to a non-flat transfer function.
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Affiliation(s)
- William Paul
- IBM Research Division, Almaden Research Center, 650 Harry Road, San Jose, California 95120, USA
| | - Susanne Baumann
- IBM Research Division, Almaden Research Center, 650 Harry Road, San Jose, California 95120, USA
| | - Christopher P Lutz
- IBM Research Division, Almaden Research Center, 650 Harry Road, San Jose, California 95120, USA
| | - Andreas J Heinrich
- IBM Research Division, Almaden Research Center, 650 Harry Road, San Jose, California 95120, USA
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Abstract
We combined the high-energy resolution of conventional spin resonance (here ~10 nano-electron volts) with scanning tunneling microscopy to measure electron paramagnetic resonance of individual iron (Fe) atoms placed on a magnesium oxide film. We drove the spin resonance with an oscillating electric field (20 to 30 gigahertz) between tip and sample. The readout of the Fe atom's quantum state was performed by spin-polarized detection of the atomic-scale tunneling magnetoresistance. We determine an energy relaxation time of T1 ≈ 100 microseconds and a phase-coherence time of T2 ≈ 210 nanoseconds. The spin resonance signals of different Fe atoms differ by much more than their resonance linewidth; in a traditional ensemble measurement, this difference would appear as inhomogeneous broadening.
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Affiliation(s)
- Susanne Baumann
- IBM Research Division, Almaden Research Center, 650 Harry Road, San Jose, CA 95120, USA. Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland.
| | - William Paul
- IBM Research Division, Almaden Research Center, 650 Harry Road, San Jose, CA 95120, USA.
| | - Taeyoung Choi
- IBM Research Division, Almaden Research Center, 650 Harry Road, San Jose, CA 95120, USA
| | - Christopher P Lutz
- IBM Research Division, Almaden Research Center, 650 Harry Road, San Jose, CA 95120, USA
| | - Arzhang Ardavan
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK
| | - Andreas J Heinrich
- IBM Research Division, Almaden Research Center, 650 Harry Road, San Jose, CA 95120, USA
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32
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Baumann S, Donati F, Stepanow S, Rusponi S, Paul W, Gangopadhyay S, Rau IG, Pacchioni GE, Gragnaniello L, Pivetta M, Dreiser J, Piamonteze C, Lutz CP, Macfarlane RM, Jones BA, Gambardella P, Heinrich AJ, Brune H. Origin of Perpendicular Magnetic Anisotropy and Large Orbital Moment in Fe Atoms on MgO. Phys Rev Lett 2015; 115:237202. [PMID: 26684139 DOI: 10.1103/physrevlett.115.237202] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Indexed: 06/05/2023]
Abstract
We report on the magnetic properties of individual Fe atoms deposited on MgO(100) thin films probed by x-ray magnetic circular dichroism and scanning tunneling spectroscopy. We show that the Fe atoms have strong perpendicular magnetic anisotropy with a zero-field splitting of 14.0±0.3 meV/atom. This is a factor of 10 larger than the interface anisotropy of epitaxial Fe layers on MgO and the largest value reported for Fe atoms adsorbed on surfaces. The interplay between the ligand field at the O adsorption sites and spin-orbit coupling is analyzed by density functional theory and multiplet calculations, providing a comprehensive model of the magnetic properties of Fe atoms in a low-symmetry bonding environment.
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Affiliation(s)
- S Baumann
- IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120, USA
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
| | - F Donati
- Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne (EPFL), Station 3, CH-1015 Lausanne, Switzerland
| | - S Stepanow
- Department of Materials, ETH Zürich, Hönggerbergring 64, CH-8093 Zürich, Switzerland
| | - S Rusponi
- Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne (EPFL), Station 3, CH-1015 Lausanne, Switzerland
| | - W Paul
- IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120, USA
| | - S Gangopadhyay
- IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120, USA
- Department of Physics, University of California, Davis, California 95616, USA
| | - I G Rau
- IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120, USA
| | - G E Pacchioni
- Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne (EPFL), Station 3, CH-1015 Lausanne, Switzerland
| | - L Gragnaniello
- Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne (EPFL), Station 3, CH-1015 Lausanne, Switzerland
| | - M Pivetta
- Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne (EPFL), Station 3, CH-1015 Lausanne, Switzerland
| | - J Dreiser
- Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne (EPFL), Station 3, CH-1015 Lausanne, Switzerland
- Swiss Light Source (SLS), Paul Scherrer Institute (PSI), CH-5232 Villigen PSI, Switzerland
| | - C Piamonteze
- Swiss Light Source (SLS), Paul Scherrer Institute (PSI), CH-5232 Villigen PSI, Switzerland
| | - C P Lutz
- IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120, USA
| | - R M Macfarlane
- IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120, USA
| | - B A Jones
- IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120, USA
| | - P Gambardella
- Department of Materials, ETH Zürich, Hönggerbergring 64, CH-8093 Zürich, Switzerland
| | - A J Heinrich
- IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120, USA
| | - H Brune
- Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne (EPFL), Station 3, CH-1015 Lausanne, Switzerland
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33
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Ernst KH, Baumann S, Lutz CP, Seibel J, Zoppi L, Heinrich AJ. Pasteur's Experiment Performed at the Nanoscale: Manual Separation of Chiral Molecules, One by One. Nano Lett 2015; 15:5388-5392. [PMID: 26121366 DOI: 10.1021/acs.nanolett.5b01762] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Understanding the principles of molecular recognition is a difficult task and calls for investigation of appropriate model systems. Using the manipulation capabilities of scanning tunneling microscopy (STM) we analyzed the chiral recognition in self-assembled dimers of helical hydrocarbons at the single molecule level. After manual separation of the two molecules of a dimer with a molecule-terminated STM tip on a Cu(111) surface, their handedness was subsequently determined with a metal atom-terminated tip. We find that these molecules strongly prefer to form heterochiral pairs. Our study shows that single molecule manipulation is a valuable tool to understand intermolecular recognition at surfaces.
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Affiliation(s)
- Karl-Heinz Ernst
- †Nanoscale Materials Science, Empa, Swiss Federal Laboratories for Materials Testing and Research, Überlandstrasse 129, CH-8600 Dübendorf, Switzerland
- ‡IBM Almaden Research Center, 650 Harry Road, San Jose, California-95120, United States
- §Department of Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - Susanne Baumann
- ‡IBM Almaden Research Center, 650 Harry Road, San Jose, California-95120, United States
- ∥Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
| | - Christopher P Lutz
- ‡IBM Almaden Research Center, 650 Harry Road, San Jose, California-95120, United States
| | - Johannes Seibel
- †Nanoscale Materials Science, Empa, Swiss Federal Laboratories for Materials Testing and Research, Überlandstrasse 129, CH-8600 Dübendorf, Switzerland
| | - Laura Zoppi
- §Department of Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - Andreas J Heinrich
- ‡IBM Almaden Research Center, 650 Harry Road, San Jose, California-95120, United States
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Abstract
Spin-resolved scanning tunneling microscopy is employed to quantitatively determine the spin polarization of the magnetic field-split Kondo state. Tunneling conductance spectra of a Kondo-screened magnetic atom are evaluated within a simple model taking into account inelastic tunneling due to spin excitations and two Kondo peaks positioned symmetrically around the Fermi energy. We fit the spin state of the Kondo-screened atom with a spin Hamiltonian independent of the Kondo effect and account for Zeeman splitting of the Kondo peak in the magnetic field. We find that the width and the height of the Kondo peaks scales with the Zeeman energy. Our observations are consistent with full spin polarization of the Kondo peaks, i.e., a majority spin peak below the Fermi energy and a minority spin peak above.
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Affiliation(s)
| | - Markus Ternes
- Max-Planck Institute for Solid State Research, 70569 Stuttgart, Germany
| | - Sebastian Loth
- Max-Planck Institute for Solid State Research, 70569 Stuttgart, Germany
- Max-Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany
| | - Christopher P Lutz
- IBM Research Division, Almaden Research Center, San Jose, California 95120, USA
| | - Andreas J Heinrich
- IBM Research Division, Almaden Research Center, San Jose, California 95120, USA
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Rau IG, Baumann S, Rusponi S, Donati F, Stepanow S, Gragnaniello L, Dreiser J, Piamonteze C, Nolting F, Gangopadhyay S, Albertini OR, Macfarlane RM, Lutz CP, Jones BA, Gambardella P, Heinrich AJ, Brune H. Reaching the magnetic anisotropy limit of a 3d metal atom. Science 2014; 344:988-92. [PMID: 24812206 DOI: 10.1126/science.1252841] [Citation(s) in RCA: 269] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Designing systems with large magnetic anisotropy is critical to realize nanoscopic magnets. Thus far, the magnetic anisotropy energy per atom in single-molecule magnets and ferromagnetic films remains typically one to two orders of magnitude below the theoretical limit imposed by the atomic spin-orbit interaction. We realized the maximum magnetic anisotropy for a 3d transition metal atom by coordinating a single Co atom to the O site of an MgO(100) surface. Scanning tunneling spectroscopy reveals a record-high zero-field splitting of 58 millielectron volts as well as slow relaxation of the Co atom's magnetization. This striking behavior originates from the dominating axial ligand field at the O adsorption site, which leads to out-of-plane uniaxial anisotropy while preserving the gas-phase orbital moment of Co, as observed with x-ray magnetic circular dichroism.
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Affiliation(s)
- Ileana G Rau
- IBM Almaden Research Center, 650 Harry Road, San Jose, CA 95120, USA
| | - Susanne Baumann
- IBM Almaden Research Center, 650 Harry Road, San Jose, CA 95120, USA. Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
| | - Stefano Rusponi
- Institute of Condensed Matter Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 3, CH-1015 Lausanne, Switzerland
| | - Fabio Donati
- Institute of Condensed Matter Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 3, CH-1015 Lausanne, Switzerland
| | - Sebastian Stepanow
- Department of Materials, Eidgenössische Technische Hochschule (ETH) Zürich, Hönggerbergring 64, CH-8093 Zürich, Switzerland
| | - Luca Gragnaniello
- Institute of Condensed Matter Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 3, CH-1015 Lausanne, Switzerland
| | - Jan Dreiser
- Institute of Condensed Matter Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 3, CH-1015 Lausanne, Switzerland. Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - Cinthia Piamonteze
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - Frithjof Nolting
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | | | - Oliver R Albertini
- IBM Almaden Research Center, 650 Harry Road, San Jose, CA 95120, USA. Department of Physics, Georgetown University, 3700 O Street NW, Washington, DC 20057, USA
| | | | | | - Barbara A Jones
- IBM Almaden Research Center, 650 Harry Road, San Jose, CA 95120, USA
| | - Pietro Gambardella
- Department of Materials, Eidgenössische Technische Hochschule (ETH) Zürich, Hönggerbergring 64, CH-8093 Zürich, Switzerland.
| | | | - Harald Brune
- Institute of Condensed Matter Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 3, CH-1015 Lausanne, Switzerland.
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Choi T, Badal M, Loth S, Yoo JW, Lutz CP, Heinrich AJ, Epstein AJ, Stroud DG, Gupta JA. Magnetism in single metalloorganic complexes formed by atom manipulation. Nano Lett 2014; 14:1196-1201. [PMID: 24490665 DOI: 10.1021/nl404054v] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The magnetic properties of molecular structures can be tailored by chemical synthesis or bottom-up assembly at the atomic scale. We used scanning tunneling microscopy to study charge and spin transfer in individual complexes of transition metals with the charge acceptor, tetracyanoethylene (TCNE). The complexes were formed on a thin insulator, Cu2N on Cu(100), by manipulation of individual atoms and molecules. The Cu2N layer decouples the complexes from Cu electron density, enabling direct imaging of the TCNE molecular orbitals as well as spin-flip inelastic electron tunneling spectroscopy. Results were obtained at low temperature down to 1 K and in magnetic fields up to 7 T in order to resolve splitting of spin states in the complexes. We also performed spin-polarized density functional theory calculations to compare with the experimental data. Our results indicate that charge transfer to TCNE leads to a change in spin magnitude, Kondo resonance, and magnetic anisotropy for the metal atoms.
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Affiliation(s)
- T Choi
- Department of Physics, The Ohio State University , Columbus, Ohio 43210, United States
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37
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Baumann S, Rau IG, Loth S, Lutz CP, Heinrich AJ. Measuring the three-dimensional structure of ultrathin insulating films at the atomic scale. ACS Nano 2014; 8:1739-1744. [PMID: 24377286 DOI: 10.1021/nn4061034] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The increasing technological importance of thin insulating layers calls for a thorough understanding of their structure. Here we apply scanning probe methods to investigate the structure of ultrathin magnesium oxide (MgO) which is the insulating material of choice in spintronic applications. A combination of force and current measurements gives high spatial resolution maps of the local three-dimensional insulator structure. When force measurements are not available, a lower spatial resolution can be obtained from tunneling images at different voltages. These broadly applicable techniques reveal a previously unknown complexity in the structure of MgO on Ag(001), such as steps in the insulator-metal interface.
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Affiliation(s)
- Susanne Baumann
- IBM Almaden Research Center , 650 Harry Road, San Jose, California 95120, United States
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38
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Abstract
Control of magnetism on the atomic scale is becoming essential as data storage devices are miniaturized. We show that antiferromagnetic nanostructures, composed of just a few Fe atoms on a surface, exhibit two magnetic states, the Néel states, that are stable for hours at low temperature. For the smallest structures, we observed transitions between Néel states due to quantum tunneling of magnetization. We sensed the magnetic states of the designed structures using spin-polarized tunneling and switched between them electrically with nanosecond speed. Tailoring the properties of neighboring antiferromagnetic nanostructures enables a low-temperature demonstration of dense nonvolatile storage of information.
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Affiliation(s)
- Sebastian Loth
- IBM Research Division, Almaden Research Center, 650 Harry Road, San Jose, CA 95120, USA.
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Ternes M, González C, Lutz CP, Hapala P, Giessibl FJ, Jelínek P, Heinrich AJ. Interplay of conductance, force, and structural change in metallic point contacts. Phys Rev Lett 2011; 106:016802. [PMID: 21231763 DOI: 10.1103/physrevlett.106.016802] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Indexed: 05/12/2023]
Abstract
The coupling between two atomically sharp nanocontacts provides tunable access to a fundamental underlying interaction: the formation of the bond between two atoms as they are brought into contact. Here we report a detailed experimental and theoretical analysis of the relation between the chemical force and the tunneling current during bond formation in atom-scale metallic junctions and their dependence on distance, junction structure, and material. We found that the short-range force as well as the conductance in two prototypical metal junctions depend exponentially on the distance and that they have essentially the same exponents. In the transition regime between tunneling and point contact, large short-range forces generate structural relaxations which are concomitant with modifications of the surface electronic structure and the collapse of the tunneling barrier.
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Affiliation(s)
- Markus Ternes
- IBM Research Division, Almaden Research Center, 650 Harry Road, San Jose, California 95120, USA.
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40
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Otte AF, Ternes M, Loth S, Lutz CP, Hirjibehedin CF, Heinrich AJ. Spin excitations of a Kondo-screened atom coupled to a second magnetic atom. Phys Rev Lett 2009; 103:107203. [PMID: 19792339 DOI: 10.1103/physrevlett.103.107203] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2009] [Indexed: 05/07/2023]
Abstract
Screening the electron spin of a magnetic atom via spin coupling to conduction electrons results in a strong resonant peak in the density of states at the Fermi energy, the Kondo resonance. We show that magnetic coupling of a Kondo atom to another unscreened magnetic atom can split the Kondo resonance into two peaks. Inelastic spin excitation spectroscopy with scanning tunneling microscopy is used to probe the Kondo effect of a Co atom, supported on a thin insulating layer on a Cu substrate, that is weakly coupled to a nearby Fe atom to form an inhomogeneous dimer. The Kondo peak is split by interaction with the non-Kondo atom, but can be reconstituted with a magnetic field of suitable magnitude and direction. Quantitative modeling shows that this magnetic field results in a spin-level degeneracy in the dimer, which enables the Kondo effect to occur.
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Affiliation(s)
- A F Otte
- IBM Research Division, Almaden Research Center, San Jose, California 95120, USA
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41
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Affiliation(s)
- Andreas J Heinrich
- Almaden Research Center, IBM Research Division, San Jose, CA 95120, USA.
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Abstract
The present topical review focuses on recent advances concerning an intriguing phenomenon in condensed matter physics, the scattering of conduction electrons at the localized spin of a magnetic impurity: the Kondo effect. Spectroscopic signatures of this effect have been observed in the past by high-resolution photoemission which, however, has the drawback of averaging over a typical surface area of 1 mm(2). By combining the atomic-scale spatial resolution of the scanning tunneling microscope (STM) with an energy resolution of a few tens of µeV achievable nowadays in scanning tunneling spectroscopy (STS), and by exposing the magnetic adatom to external magnetic fields, our understanding of the interaction of a single magnetic impurity with the conduction electrons of the nonmagnetic host has been considerably deepened. New insight has emerged by taking advantage of quantum size effects in the metallic support and by decoupling the magnetic adatom from the supporting host metal, for instance by embedding it inside a molecule or by separating it by an ultrathin insulating film from the metal surface. In this way, Kondo resonances and Kondo temperatures can be tailored and manipulated by changing the local density of states of the environment. In the weak coupling limit between a Kondo impurity and a superconductor only a convolution of tip and sample DOS is observed while for strongly coupled systems midgap states appear, indicating superconducting pair breaking. Magnetic impurities with co-adsorbed hydrogen on metallic surfaces show pseudo-Kondo resonances owing to very low-energy vibrational excitations detected by inelastic tunneling spectroscopy. One of the most recent achievements in the field has been the clarification of the role of magnetic anisotropy in the Kondo effect for localized spin systems with a spin larger than S = 1/2.
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Affiliation(s)
- Markus Ternes
- IBM Almaden Research Center, 650 Harry Road, San Jose, CA, USA. Institut de Physique des Nanostructures, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
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43
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Abstract
Manipulation of individual atoms and molecules by scanning probe microscopy offers the ability of controlled assembly at the single-atom scale. However, the driving forces behind atomic manipulation have not yet been measured. We used an atomic force microscope to measure the vertical and lateral forces exerted on individual adsorbed atoms or molecules by the probe tip. We found that the force that it takes to move an atom depends strongly on the adsorbate and the surface. Our results indicate that for moving metal atoms on metal surfaces, the lateral force component plays the dominant role. Furthermore, measuring spatial maps of the forces during manipulation yielded the full potential energy landscape of the tip-sample interaction.
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Affiliation(s)
- Markus Ternes
- IBM Research Division, Almaden Research Center, 650 Harry Road, San Jose, CA 95120, USA.
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Hirjibehedin CF, Lin CY, Otte AF, Ternes M, Lutz CP, Jones BA, Heinrich AJ. Large Magnetic Anisotropy of a Single Atomic Spin Embedded in a Surface Molecular Network. Science 2007; 317:1199-203. [PMID: 17761877 DOI: 10.1126/science.1146110] [Citation(s) in RCA: 496] [Impact Index Per Article: 29.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Magnetic anisotropy allows magnets to maintain their direction of magnetization over time. Using a scanning tunneling microscope to observe spin excitations, we determined the orientation and strength of the anisotropies of individual iron and manganese atoms on a thin layer of copper nitride. The relative intensities of the inelastic tunneling processes are consistent with dipolar interactions, as seen for inelastic neutron scattering. First-principles calculations indicate that the magnetic atoms become incorporated into a polar covalent surface molecular network in the copper nitride. These structures, which provide atom-by-atom accessibility via local probes, have the potential for engineering anisotropies large enough to produce stable magnetization at low temperatures for a single atomic spin.
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Abstract
We used a scanning tunneling microscope to probe the interactions between spins in individual atomic-scale magnetic structures. Linear chains of 1 to 10 manganese atoms were assembled one atom at a time on a thin insulating layer, and the spin excitation spectra of these structures were measured with inelastic electron tunneling spectroscopy. We observed excitations of the coupled atomic spins that can change both the total spin and its orientation. Comparison with a model spin-interaction Hamiltonian yielded the collective spin configuration and the strength of the coupling between the atomic spins.
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Affiliation(s)
- Cyrus F Hirjibehedin
- IBM Research Division, Almaden Research Center, 650 Harry Road, San Jose, CA 95120, USA.
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46
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Abstract
We demonstrate the ability to measure the energy required to flip the spin of single adsorbed atoms. A low-temperature, high-magnetic field scanning tunneling microscope was used to measure the spin excitation spectra of individual manganese atoms adsorbed on Al2O3 islands on a NiAl surface. We find pronounced variations of the spin-flip spectra for manganese atoms in different local environments.
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Affiliation(s)
- A J Heinrich
- IBM Research Division, Almaden Research Center, 650 Harry Road, San Jose, CA 95120, USA.
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47
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Eigler DM, Lutz CP, Crommie MF, Manoharan HC, Heinrich AJ, Gupta JA. Information transport and computation in nanometre-scale structures. Philos Trans A Math Phys Eng Sci 2004; 362:1135-1147. [PMID: 15306466 DOI: 10.1098/rsta.2004.1367] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We discuss two examples of novel information-transport and processing mechanisms in nanometre-scale structures. The local modulation and detection of a quantum state can be used for information transport at the nanometre length-scale, an effect we call a 'quantum mirage'. We demonstrate that, unlike conventional electronic information transport using wires, the quantum mirage can be used to pass multiple channels of information through the same volume of a solid. We discuss a new class of nanometre-scale structures called 'molecule cascades', and show how they may be used to implement a general-purpose binary-logic computer in which all of the circuitry is at the nanometre length-scale.
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Affiliation(s)
- D M Eigler
- IBM Research Division, Almaden Research Center, 650 Harry Road, San Jose, CA 95120, USA.
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48
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Abstract
Carbon monoxide molecules were arranged in atomically precise configurations, which we call "molecule cascades," where the motion of one molecule causes the subsequent motion of another, and so on in a cascade of motion similar to a row of toppling dominoes. Isotopically pure cascades were assembled on a copper (111) surface with a low-temperature scanning tunneling microscope. The hopping rate of carbon monoxide molecules in cascades was found to be independent of temperature below 6 kelvin and to exhibit a pronounced isotope effect, hallmarks of a quantum tunneling process. At higher temperatures, we observed a thermally activated hopping rate with an anomalously low Arrhenius prefactor that we interpret as tunneling from excited vibrational states. We present a cascade-based computation scheme that has all of the devices and interconnects required for the one-time computation of an arbitrary logic function. Logic gates and other devices were implemented by engineered arrangements of molecules at the intersections of cascades. We demonstrate a three-input sorter that uses several AND gates and OR gates, as well as the crossover and fan-out units needed to connect them.
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Affiliation(s)
- A J Heinrich
- IBM Research Division, Almaden Research Center, 650 Harry Road, San Jose, CA 95120, USA.
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