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Li W, Wang J, Zhang J, Meng W, Xie C, Hou Y, Xia Z, Lu Q. Atomic-Resolution Imaging of Micron-Sized Samples Realized by High Magnetic Field Scanning Tunneling Microscopy. MICROMACHINES 2023; 14:287. [PMID: 36837986 PMCID: PMC9961884 DOI: 10.3390/mi14020287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 01/03/2023] [Accepted: 01/19/2023] [Indexed: 06/18/2023]
Abstract
Scanning tunneling microscopy (STM) can image material surfaces with atomic resolution, making it a useful tool in the areas of physics and materials. Many materials are synthesized at micron size, especially few-layer materials. Limited by their complex structure, very few STMs are capable of directly positioning and imaging a micron-sized sample with atomic resolution. Traditional STMs are designed to study the material behavior induced by temperature variation, while the physical properties induced by magnetic fields are rarely studied. In this paper, we present the design and construction of an atomic-resolution STM that can operate in a 9 T high magnetic field. More importantly, the homebuilt STM is capable of imaging micron-sized samples. The performance of the STM is demonstrated by high-quality atomic images obtained on a graphite surface, with low drift rates in the X-Y plane and Z direction. The atomic-resolution image obtained on a 32-μm graphite flake illustrates the new STM's ability of positioning and imaging micron-sized samples. Finally, we present atomic resolution images at a magnetic field range from 0 T to 9 T. The above advantages make our STM a promising tool for investigating the quantum hall effect of micron-sized layered materials.
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Affiliation(s)
- Weixuan Li
- College of Metrology and Measurement Engineering, China Jiliang University (CJLU), Hangzhou 310018, China
| | - Jihao Wang
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China
- High Magnetic Field Laboratory of Anhui Province, Chinese Academy of Sciences, Hefei 230031, China
| | - Jing Zhang
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China
- High Magnetic Field Laboratory of Anhui Province, Chinese Academy of Sciences, Hefei 230031, China
| | - Wenjie Meng
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China
- High Magnetic Field Laboratory of Anhui Province, Chinese Academy of Sciences, Hefei 230031, China
| | - Caihong Xie
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China
- High Magnetic Field Laboratory of Anhui Province, Chinese Academy of Sciences, Hefei 230031, China
| | - Yubin Hou
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China
- High Magnetic Field Laboratory of Anhui Province, Chinese Academy of Sciences, Hefei 230031, China
| | - Zhigang Xia
- College of Metrology and Measurement Engineering, China Jiliang University (CJLU), Hangzhou 310018, China
| | - Qingyou Lu
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China
- High Magnetic Field Laboratory of Anhui Province, Chinese Academy of Sciences, Hefei 230031, China
- Anhui Laboratory of Advanced Photon Science and Technology, University of Science and Technology of China, Hefei 230026, China
- Hefei Science Center, Chinese Academy of Sciences, Hefei 230031, China
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2
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Fernández-Lomana M, Wu B, Martín-Vega F, Sánchez-Barquilla R, Álvarez-Montoya R, Castilla JM, Navarrete J, Marijuan JR, Herrera E, Suderow H, Guillamón I. Millikelvin scanning tunneling microscope at 20/22 T with a graphite enabled stick-slip approach and an energy resolution below 8 μeV: Application to conductance quantization at 20 T in single atom point contacts of Al and Au and to the charge density wave of 2H-NbSe 2. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:093701. [PMID: 34598511 DOI: 10.1063/5.0059394] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Accepted: 08/21/2021] [Indexed: 06/13/2023]
Abstract
We describe a scanning tunneling microscope (STM) that operates at magnetic fields up to 22 T and temperatures down to 80 mK. We discuss the design of the STM head, with an improved coarse approach, the vibration isolation system, and efforts to improve the energy resolution using compact filters for multiple lines. We measure the superconducting gap and Josephson effect in aluminum and show that we can resolve features in the density of states as small as 8 μeV. We measure the quantization of conductance in atomic size contacts and make atomic resolution and density of states images in the layered material 2H-NbSe2. The latter experiments are performed by continuously operating the STM at magnetic fields of 20 T in periods of several days without interruption.
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Affiliation(s)
- Marta Fernández-Lomana
- Laboratorio de Bajas Temperaturas y Altos Campos Magnéticos, Unidad Asociada (UAM/CSIC), Departamento de Física de la Materia Condensada, Instituto Nicolás Cabrera and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | - Beilun Wu
- Laboratorio de Bajas Temperaturas y Altos Campos Magnéticos, Unidad Asociada (UAM/CSIC), Departamento de Física de la Materia Condensada, Instituto Nicolás Cabrera and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | - Francisco Martín-Vega
- Laboratorio de Bajas Temperaturas y Altos Campos Magnéticos, Unidad Asociada (UAM/CSIC), Departamento de Física de la Materia Condensada, Instituto Nicolás Cabrera and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | - Raquel Sánchez-Barquilla
- Laboratorio de Bajas Temperaturas y Altos Campos Magnéticos, Unidad Asociada (UAM/CSIC), Departamento de Física de la Materia Condensada, Instituto Nicolás Cabrera and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | - Rafael Álvarez-Montoya
- Laboratorio de Bajas Temperaturas y Altos Campos Magnéticos, Unidad Asociada (UAM/CSIC), Departamento de Física de la Materia Condensada, Instituto Nicolás Cabrera and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | - José María Castilla
- Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | - José Navarrete
- SEGAINVEX, Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | | | - Edwin Herrera
- Laboratorio de Bajas Temperaturas y Altos Campos Magnéticos, Unidad Asociada (UAM/CSIC), Departamento de Física de la Materia Condensada, Instituto Nicolás Cabrera and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | - Hermann Suderow
- Laboratorio de Bajas Temperaturas y Altos Campos Magnéticos, Unidad Asociada (UAM/CSIC), Departamento de Física de la Materia Condensada, Instituto Nicolás Cabrera and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | - Isabel Guillamón
- Laboratorio de Bajas Temperaturas y Altos Campos Magnéticos, Unidad Asociada (UAM/CSIC), Departamento de Física de la Materia Condensada, Instituto Nicolás Cabrera and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, E-28049 Madrid, Spain
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3
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Esat T, Borgens P, Yang X, Coenen P, Cherepanov V, Raccanelli A, Tautz FS, Temirov R. A millikelvin scanning tunneling microscope in ultra-high vacuum with adiabatic demagnetization refrigeration. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:063701. [PMID: 34243501 DOI: 10.1063/5.0050532] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 05/23/2021] [Indexed: 06/13/2023]
Abstract
We present the design and performance of an ultra-high vacuum scanning tunneling microscope (STM) that uses adiabatic demagnetization of electron magnetic moments for controlling its operating temperature ranging between 30 mK and 1 K with an accuracy of up to 7 μK rms. At the same time, high magnetic fields of up to 8 T can be applied perpendicular to the sample surface. The time available for STM experiments at 50 mK is longer than 20 h, at 100 mK about 40 h. The single-shot adiabatic demagnetization refrigerator can be regenerated automatically within 7 h while keeping the STM temperature below 5 K. The whole setup is located in a vibrationally isolated, electromagnetically shielded laboratory with no mechanical pumping lines penetrating its isolation walls. The 1 K pot of the adiabatic demagnetization refrigeration cryostat can be operated silently for more than 20 days in a single-shot mode using a custom-built high-capacity cryopump. A high degree of vibrational decoupling together with the use of a specially designed minimalistic STM head provides outstanding mechanical stability, demonstrated by the tunneling current noise, STM imaging, and scanning tunneling spectroscopy measurements, all performed on an atomically clean Al(100) surface.
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Affiliation(s)
- Taner Esat
- Peter Grünberg Institute (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Peter Borgens
- Peter Grünberg Institute (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Xiaosheng Yang
- Peter Grünberg Institute (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Peter Coenen
- Peter Grünberg Institute (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Vasily Cherepanov
- Peter Grünberg Institute (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
| | | | - F Stefan Tautz
- Peter Grünberg Institute (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Ruslan Temirov
- Peter Grünberg Institute (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
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4
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Kohsaka Y. Removing background and estimating a unit height of atomic steps from a scanning probe microscopy image using a statistical model. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:033702. [PMID: 33820037 DOI: 10.1063/5.0038852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Accepted: 02/20/2021] [Indexed: 06/12/2023]
Abstract
We present a statistical method to remove background and estimate a unit height of atomic steps of an image obtained using a scanning probe microscope. We adopt a mixture model consisting of multiple statistical distributions to describe an image. This statistical approach provides a comprehensive way to subtract a background surface even in the presence of atomic steps as well as to evaluate terrace heights in a single framework. Moreover, it also enables us to extract further quantitative information by introducing additional prior knowledge about the image. An example of this extension is estimating a unit height of atomic steps together with the terrace heights. We demonstrate the capability of our method for a topographic image of a Cu(111) surface taken using a scanning tunneling microscope. The background subtraction corrects all terraces to be parallel to a horizontal plane, and the precision of the estimated unit height reaches the order of a picometer. An open-source implementation of our method is available on the web.
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Affiliation(s)
- Yuhki Kohsaka
- RIKEN Center for Emergent Matter Science, Wako, Saitama 351-0198, Japan
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5
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van Weerdenburg WMJ, Steinbrecher M, van Mullekom NPE, Gerritsen JW, von Allwörden H, Natterer FD, Khajetoorians AA. A scanning tunneling microscope capable of electron spin resonance and pump-probe spectroscopy at mK temperature and in vector magnetic field. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:033906. [PMID: 33820009 DOI: 10.1063/5.0040011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 02/19/2021] [Indexed: 06/12/2023]
Abstract
In the last decade, detecting spin dynamics at the atomic scale has been enabled by combining techniques such as electron spin resonance (ESR) or pump-probe spectroscopy with scanning tunneling microscopy (STM). Here, we demonstrate an ultra-high vacuum STM operational at milliKelvin (mK) temperatures and in a vector magnetic field capable of both ESR and pump-probe spectroscopy. By implementing GHz compatible cabling, we achieve appreciable RF amplitudes at the junction while maintaining the mK base temperature and high energy resolution. We demonstrate the successful operation of our setup by utilizing two experimental ESR modes (frequency sweep and magnetic field sweep) on an individual TiH molecule on MgO/Ag(100) and extract the effective g-factor. We trace the ESR transitions down to MHz into an unprecedented low frequency band enabled by the mK base temperature. We also implement an all-electrical pump-probe scheme based on waveform sequencing suited for studying dynamics down to the nanoseconds range. We benchmark our system by detecting the spin relaxation time T1 of individual Fe atoms on MgO/Ag(100) and note a field strength and orientation dependent relaxation time.
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Affiliation(s)
| | - Manuel Steinbrecher
- Institute for Molecules and Materials, Radboud University, 6525 AJ Nijmegen, The Netherlands
| | - Niels P E van Mullekom
- Institute for Molecules and Materials, Radboud University, 6525 AJ Nijmegen, The Netherlands
| | - Jan W Gerritsen
- Institute for Molecules and Materials, Radboud University, 6525 AJ Nijmegen, The Netherlands
| | - Henning von Allwörden
- Institute for Molecules and Materials, Radboud University, 6525 AJ Nijmegen, The Netherlands
| | - Fabian D Natterer
- Department of Physics, University of Zurich, CH-8057 Zurich, Switzerland
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6
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Schwenk J, Kim S, Berwanger J, Ghahari F, Walkup D, Slot MR, Le ST, Cullen WG, Blankenship SR, Vranjkovic S, Hug HJ, Kuk Y, Giessibl FJ, Stroscio JA. Achieving μeV tunneling resolution in an in-operando scanning tunneling microscopy, atomic force microscopy, and magnetotransport system for quantum materials research. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2020; 91:071101. [PMID: 32752869 PMCID: PMC7678032 DOI: 10.1063/5.0005320] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Accepted: 06/04/2020] [Indexed: 06/11/2023]
Abstract
Research in new quantum materials requires multi-mode measurements spanning length scales, correlations of atomic-scale variables with a macroscopic function, and spectroscopic energy resolution obtainable only at millikelvin temperatures, typically in a dilution refrigerator. In this article, we describe a multi-mode instrument achieving a μeV tunneling resolution with in-operando measurement capabilities of scanning tunneling microscopy, atomic force microscopy, and magnetotransport inside a dilution refrigerator operating at 10 mK. We describe the system in detail including a new scanning probe microscope module design and sample and tip transport systems, along with wiring, radio-frequency filtering, and electronics. Extensive benchmarking measurements were performed using superconductor-insulator-superconductor tunnel junctions, with Josephson tunneling as a noise metering detector. After extensive testing and optimization, we have achieved less than 8 μeV instrument resolving capability for tunneling spectroscopy, which is 5-10 times better than previous instrument reports and comparable to the quantum and thermal limits set by the operating temperature at 10 mK.
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Affiliation(s)
- Johannes Schwenk
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
- Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, MD 20742, USA
| | - Sungmin Kim
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
- Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, MD 20742, USA
| | - Julian Berwanger
- Institute of Experimental and Applied Physics, University of Regensburg, 93053 Regensburg, Germany
| | - Fereshte Ghahari
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
- Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, MD 20742, USA
| | - Daniel Walkup
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
- Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, MD 20742, USA
| | - Marlou R. Slot
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
- Department of Physics, Georgetown University, Washington, DC 20007, USA
| | - Son T. Le
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
- Theiss Research, La Jolla, CA 92037, USA
| | - William G. Cullen
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Steven R. Blankenship
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Sasa Vranjkovic
- Institute of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
| | - Hans J. Hug
- Institute of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
| | - Young Kuk
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Korea
| | - Franz J. Giessibl
- Institute of Experimental and Applied Physics, University of Regensburg, 93053 Regensburg, Germany
| | - Joseph A. Stroscio
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
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7
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Wong D, Jeon S, Nuckolls KP, Oh M, Kingsley SCJ, Yazdani A. A modular ultra-high vacuum millikelvin scanning tunneling microscope. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2020; 91:023703. [PMID: 32113373 DOI: 10.1063/1.5132872] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Accepted: 01/18/2020] [Indexed: 06/10/2023]
Abstract
We describe the design, construction, and performance of an ultra-high vacuum (UHV) scanning tunneling microscope (STM) capable of imaging at dilution-refrigerator temperatures and equipped with a vector magnet. The primary objective of our design is to achieve a high level of modularity by partitioning the STM system into a set of easily separable, interchangeable components. This naturally segregates the UHV needs of STM instrumentation from the typically non-UHV construction of a dilution refrigerator, facilitating the usage of non-UHV materials while maintaining a fully bakeable UHV chamber that houses the STM. The modular design also permits speedy removal of the microscope head from the rest of the system, allowing for repairs, modifications, and even replacement of the entire microscope head to be made at any time without warming the cryostat or compromising the vacuum. Without using cryogenic filters, we measured an electron temperature of 184 mK on a superconducting Al(100) single crystal.
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Affiliation(s)
- Dillon Wong
- Joseph Henry Laboratories and Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Sangjun Jeon
- Joseph Henry Laboratories and Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Kevin P Nuckolls
- Joseph Henry Laboratories and Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Myungchul Oh
- Joseph Henry Laboratories and Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Simon C J Kingsley
- Oxford Instruments, Tubney Woods, Abingdon, Oxfordshire OX13 5QX, United Kingdom
| | - Ali Yazdani
- Joseph Henry Laboratories and Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
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8
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Leeuwenhoek M, Groenewoud F, van Oosten K, Benschop T, Allan MP, Gröblacher S. Fabrication of on-chip probes for double-tip scanning tunneling microscopy. MICROSYSTEMS & NANOENGINEERING 2020; 6:99. [PMID: 34567708 PMCID: PMC8433193 DOI: 10.1038/s41378-020-00209-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Revised: 08/28/2020] [Accepted: 09/01/2020] [Indexed: 05/22/2023]
Abstract
A reduction of the interprobe distance in multiprobe and double-tip scanning tunneling microscopy to the nanometer scale has been a longstanding and technically difficult challenge. Recent multiprobe systems have allowed for significant progress by achieving distances of ~30 nm using two individually driven, traditional metal wire tips. For situations where simple alignment and fixed separation can be advantageous, we present the fabrication of on-chip double-tip devices that incorporate two mechanically fixed gold tips with a tip separation of only 35 nm. We utilize the excellent mechanical, insulating and dielectric properties of high-quality SiN as a base material to realize easy-to-implement, lithographically defined and mechanically stable tips. With their large contact pads and adjustable footprint, these novel tips can be easily integrated with most existing commercial combined STM/AFM systems.
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Affiliation(s)
- Maarten Leeuwenhoek
- Kavli Institute of Nanoscience, Department of Quantum Nanoscience, Delft University of Technology, Lorentzweg 1, 2628CJ Delft, The Netherlands
- Leiden Institute of Physics, Leiden University, Niels Bohrweg 2, 2333CA Leiden, The Netherlands
| | - Freek Groenewoud
- Leiden Institute of Physics, Leiden University, Niels Bohrweg 2, 2333CA Leiden, The Netherlands
| | - Kees van Oosten
- Leiden Institute of Physics, Leiden University, Niels Bohrweg 2, 2333CA Leiden, The Netherlands
| | - Tjerk Benschop
- Leiden Institute of Physics, Leiden University, Niels Bohrweg 2, 2333CA Leiden, The Netherlands
| | - Milan P. Allan
- Leiden Institute of Physics, Leiden University, Niels Bohrweg 2, 2333CA Leiden, The Netherlands
| | - Simon Gröblacher
- Kavli Institute of Nanoscience, Department of Quantum Nanoscience, Delft University of Technology, Lorentzweg 1, 2628CJ Delft, The Netherlands
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9
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Leeuwenhoek M, Norte RA, Bastiaans KM, Cho D, Battisti I, Blanter YM, Gröblacher S, Allan MP. Nanofabricated tips for device-based scanning tunneling microscopy. NANOTECHNOLOGY 2019; 30:335702. [PMID: 31022709 DOI: 10.1088/1361-6528/ab1c7f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
We report on the fabrication and performance of a new kind of tip for scanning tunneling microscopy. By fully incorporating a metallic tip on a silicon chip using modern micromachining and nanofabrication techniques, we realize so-called smart tips and show the possibility of device-based STM tips. Contrary to conventional etched metal wire tips, these can be integrated into lithographically defined electrical circuits. We describe a new fabrication method to create a defined apex on a silicon chip and experimentally demonstrate the high performance of the smart tips, both in stability and resolution. In situ tip preparation methods are possible and we verify that they can resolve the herringbone reconstruction and Friedel oscillations on Au(111) surfaces. We further present an overview of possible applications.
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Affiliation(s)
- Maarten Leeuwenhoek
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628CJ Delft, The Netherlands. Leiden Institute of Physics, Leiden University, Niels Bohrweg 2, 2333CA Leiden, The Netherlands
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10
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de Wit M, Welker G, Heeck K, Buters FM, Eerkens HJ, Koning G, van der Meer H, Bouwmeester D, Oosterkamp TH. Vibration isolation with high thermal conductance for a cryogen-free dilution refrigerator. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2019; 90:015112. [PMID: 30709182 DOI: 10.1063/1.5066618] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Accepted: 12/24/2018] [Indexed: 06/09/2023]
Abstract
We present the design and implementation of a mechanical low-pass filter vibration isolation used to reduce the vibrational noise in a cryogen-free dilution refrigerator operated at 10 mK, intended for scanning probe techniques. We discuss the design guidelines necessary to meet the competing requirements of having a low mechanical stiffness in combination with a high thermal conductance. We demonstrate the effectiveness of our approach by measuring the vibrational noise levels of an ultrasoft mechanical resonator positioned above a superconducting quantum interference device. Starting from a cryostat base temperature of 8 mK, the vibration isolation can be cooled to 10.5 mK, with a cooling power of 113 µW at 100 mK. We use the low vibrations and low temperature to demonstrate an effective cantilever temperature of less than 20 mK. This results in a force sensitivity of less than 500 zN/Hz and an integrated frequency noise as low as 0.4 mHz in a 1 Hz measurement bandwidth.
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Affiliation(s)
- Martin de Wit
- Leiden Institute of Physics, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands
| | - Gesa Welker
- Leiden Institute of Physics, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands
| | - Kier Heeck
- Leiden Institute of Physics, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands
| | - Frank M Buters
- Leiden Institute of Physics, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands
| | - Hedwig J Eerkens
- Leiden Institute of Physics, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands
| | - Gert Koning
- Leiden Institute of Physics, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands
| | - Harmen van der Meer
- Leiden Institute of Physics, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands
| | - Dirk Bouwmeester
- Leiden Institute of Physics, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands
| | - Tjerk H Oosterkamp
- Leiden Institute of Physics, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands
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11
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Natterer FD, Patthey F, Bilgeri T, Forrester PR, Weiss N, Brune H. Upgrade of a low-temperature scanning tunneling microscope for electron-spin resonance. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2019; 90:013706. [PMID: 30709206 DOI: 10.1063/1.5065384] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Accepted: 01/07/2019] [Indexed: 06/09/2023]
Abstract
Electron spin resonance with a scanning tunneling microscope (ESR-STM) combines the high energy resolution of spin resonance spectroscopy with the atomic scale control and spatial resolution of STM. Here we describe the upgrade of a helium-3 STM with a 2D vector-field magnet (Bz = 8.0 T, Bx = 0.8 T) to an ESR-STM. The system is capable of delivering radio frequency (RF) power to the tunnel junction at frequencies up to 30 GHz. We demonstrate magnetic field-sweep ESR for the model system TiH/MgO/Ag(100) and find a magnetic moment of (1.004 ± 0.001) μB. Our upgrade enables to toggle between a DC mode, where the STM is operated with the regular control electronics, and an ultrafast-pulsed mode that uses an arbitrary waveform generator for pump-probe spectroscopy or reading of spin-states. Both modes allow for simultaneous radiofrequency excitation, which we add via a resistive pick-off tee to the bias voltage path. The RF cabling from room temperature to the 350 mK stage has an average attenuation of 18 dB between 5 and 25 GHz. The cable segment between the 350 mK stage and the STM tip presently attenuates an additional 34-3 +5 dB from 10 to 26 GHz and 38-2 +3 dB between 20 and 30 GHz. We discuss our transmission losses and indicate ways to reduce this attenuation. We finally demonstrate how to synchronize the arrival times of RF and DC pulses coming from different paths to the STM junction, a prerequisite for future pulsed ESR experiments.
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Affiliation(s)
- Fabian D Natterer
- Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - François Patthey
- Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Tobias Bilgeri
- Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Patrick R Forrester
- Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Nicolas Weiss
- Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Harald Brune
- Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
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12
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Guan SY, Liao HS, Juang BJ, Chin SC, Chuang TM, Chang CS. The design and the performance of an ultrahigh vacuum 3He fridge-based scanning tunneling microscope with a double deck sample stage for in-situ tip treatment. Ultramicroscopy 2018; 196:180-185. [PMID: 30423505 DOI: 10.1016/j.ultramic.2018.10.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2018] [Revised: 09/25/2018] [Accepted: 10/18/2018] [Indexed: 11/20/2022]
Abstract
Scanning tunneling microscope (STM) is a powerful tool for studying the structural and electronic properties of materials at the atomic scale. The combination of low temperature and high magnetic field for STM and related spectroscopy techniques allows us to investigate the novel physical properties of materials at these extreme conditions with high energy resolution. Here, we present the construction and the performance of an ultrahigh vacuum 3He fridge-based STM system with a 7 Tesla superconducting magnet. It features a double deck sample stage on the STM head so we can clean the tip by field emission or prepare a spin-polarized tip in situ without removing the sample from the STM. It is also capable of in situ sample and tip exchange and preparation. The energy resolution of scanning tunneling spectroscopy at T = 310 mK is determined to be 400 mK by measuring the superconducting gap with a niobium tip on a gold surface. We demonstrate the performance of this STM system by imaging the bicollinear magnetic order of Fe1+xTe at T = 5 K.
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Affiliation(s)
- Syu-You Guan
- Institude of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan; Department of Physics, National Taiwan University, Taipei 10617, Taiwan.
| | - Hsien-Shun Liao
- Institude of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan; Department of Mechanical Engineering, National Taiwan University, Taipei 10617, Taiwan
| | - Bo-Jing Juang
- Institude of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan
| | - Shu-Cheng Chin
- Institude of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan
| | - Tien-Ming Chuang
- Institude of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan.
| | - Chia-Seng Chang
- Institude of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan; Department of Physics, National Taiwan University, Taipei 10617, Taiwan.
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13
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Balashov T, Meyer M, Wulfhekel W. A compact ultrahigh vacuum scanning tunneling microscope with dilution refrigeration. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:113707. [PMID: 30501324 DOI: 10.1063/1.5043636] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Accepted: 10/25/2018] [Indexed: 06/09/2023]
Abstract
We have designed and built a scanning tunneling microscope (STM) setup for operation at millikelvin temperatures in an ultrahigh vacuum. A compact cryostat with an integrated dilution refrigerator has been built that allows measurements at a base temperature of 25 mK in the magnetic field up to 7.5 T with low mechanical and electronic noise. The cryostat is not larger than conventional helium bath cryostats (23 and 13 l of nitrogen and helium, respectively) so that the setup does not require a large experimental hall and fits easily into a standard lab space. Mechanical vibrations with running dilution circulation were kept below 1 pm/ Hz by mechanically decoupling the STM from the cryostat and the pumping system. All electronic input lines were low-pass filtered, reducing the electronic temperature to below 100 mK, as deduced from the quasiparticle peaks of superconducting aluminum. The microscope is optically accessible in the parked position, making sample and tip exchange fast and user-friendly. For measurement, the STM is lowered 60 mm down so that the sample ends in the middle of a wet superconducting magnetic coil.
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Affiliation(s)
- T Balashov
- Physikalisches Institut, Karlsruhe Institute of Technology, Wolfgang-Gaede-Strasse 1, 76131 Karlsruhe, Germany
| | - M Meyer
- Physikalisches Institut, Karlsruhe Institute of Technology, Wolfgang-Gaede-Strasse 1, 76131 Karlsruhe, Germany
| | - W Wulfhekel
- Physikalisches Institut, Karlsruhe Institute of Technology, Wolfgang-Gaede-Strasse 1, 76131 Karlsruhe, Germany
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14
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Machida T, Kohsaka Y, Hanaguri T. A scanning tunneling microscope for spectroscopic imaging below 90 mK in magnetic fields up to 17.5 T. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:093707. [PMID: 30278760 DOI: 10.1063/1.5049619] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Accepted: 09/09/2018] [Indexed: 06/08/2023]
Abstract
We describe the development and performance of an ultra-high vacuum scanning tunneling microscope working under combined extreme conditions of ultra-low temperatures and high magnetic fields. We combined a top-loading dilution refrigerator and a standard bucket dewar with a bottom-loading superconducting magnet to achieve 4.5 days operating time, which is long enough to perform various spectroscopic-imaging measurements. To bring the effective electron temperature closer to the mixing-chamber temperature, we paid particular attention to filtering out radio-frequency noise, as well as enhancing the thermal link between the microscope unit and the mixing chamber. We estimated the lowest effective electron temperature to be below 90 mK by measuring the superconducting-gap spectrum of aluminum. We confirmed the long-term stability of the spectroscopic-imaging measurement by visualizing superconducting vortices in the cuprate superconductor Bi2Sr2CaCu2O8+δ .
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Affiliation(s)
- T Machida
- RIKEN Center for Emergent Matter Science, Wako, Saitama 351-0198, Japan
| | - Y Kohsaka
- RIKEN Center for Emergent Matter Science, Wako, Saitama 351-0198, Japan
| | - T Hanaguri
- RIKEN Center for Emergent Matter Science, Wako, Saitama 351-0198, Japan
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15
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Salazar C, Baumann D, Hänke T, Scheffler M, Kühne T, Kaiser M, Voigtländer R, Lindackers D, Büchner B, Hess C. An ultra-high vacuum scanning tunneling microscope operating at sub-Kelvin temperatures and high magnetic fields for spin-resolved measurements. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:065104. [PMID: 29960518 DOI: 10.1063/1.5027782] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We present the construction and performance of an ultra-low-temperature scanning tunneling microscope (STM), working in ultra-high vacuum (UHV) conditions and in high magnetic fields up to 9 T. The cryogenic environment of the STM is generated by a single-shot 3He magnet cryostat in combination with a 4He dewar system. At a base temperature (300 mK), the cryostat has an operation time of approximately 80 h. The special design of the microscope allows the transfer of the STM head from the cryostat to a UHV chamber system, where samples and STM tips can be easily exchanged. The UHV chambers are equipped with specific surface science treatment tools for the functionalization of samples and tips, including high-temperature treatments and thin film deposition. This, in particular, enables spin-resolved tunneling measurements. We present test measurements using well-known samples and tips based on superconductors and metallic materials such as LiFeAs, Nb, Fe, and W. The measurements demonstrate the outstanding performance of the STM with high spatial and energy resolution as well as the spin-resolved capability.
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Affiliation(s)
- C Salazar
- Leibniz Institute for Solid State and Materials Research, IFW-Dresden, Helmholtzstraße 20, 01069 Dresden, Germany
| | - D Baumann
- Leibniz Institute for Solid State and Materials Research, IFW-Dresden, Helmholtzstraße 20, 01069 Dresden, Germany
| | - T Hänke
- Leibniz Institute for Solid State and Materials Research, IFW-Dresden, Helmholtzstraße 20, 01069 Dresden, Germany
| | - M Scheffler
- Leibniz Institute for Solid State and Materials Research, IFW-Dresden, Helmholtzstraße 20, 01069 Dresden, Germany
| | - T Kühne
- Leibniz Institute for Solid State and Materials Research, IFW-Dresden, Helmholtzstraße 20, 01069 Dresden, Germany
| | - M Kaiser
- Leibniz Institute for Solid State and Materials Research, IFW-Dresden, Helmholtzstraße 20, 01069 Dresden, Germany
| | - R Voigtländer
- Leibniz Institute for Solid State and Materials Research, IFW-Dresden, Helmholtzstraße 20, 01069 Dresden, Germany
| | - D Lindackers
- Leibniz Institute for Solid State and Materials Research, IFW-Dresden, Helmholtzstraße 20, 01069 Dresden, Germany
| | - B Büchner
- Leibniz Institute for Solid State and Materials Research, IFW-Dresden, Helmholtzstraße 20, 01069 Dresden, Germany
| | - C Hess
- Leibniz Institute for Solid State and Materials Research, IFW-Dresden, Helmholtzstraße 20, 01069 Dresden, Germany
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16
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Liebmann M, Bindel JR, Pezzotta M, Becker S, Muckel F, Johnsen T, Saunus C, Ast CR, Morgenstern M. An ultrahigh-vacuum cryostat for simultaneous scanning tunneling microscopy and magneto-transport measurements down to 400 mK. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2017; 88:123707. [PMID: 29289196 DOI: 10.1063/1.4999555] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We present the design and calibration measurements of a scanning tunneling microscope setup in a 3He ultrahigh-vacuum cryostat operating at 400 mK with a hold time of 10 days. With 2.70 m in height and 4.70 m free space needed for assembly, the cryostat fits in a one-story lab building. The microscope features optical access, an xy table, in situ tip and sample exchange, and enough contacts to facilitate atomic force microscopy in tuning fork operation and simultaneous magneto-transport measurements on the sample. Hence, it enables scanning tunneling spectroscopy on microstructured samples which are tuned into preselected transport regimes. A superconducting magnet provides a perpendicular field of up to 14 T. The vertical noise of the scanning tunneling microscope amounts to 1 pmrms within a 700 Hz bandwidth. Tunneling spectroscopy using one superconducting electrode revealed an energy resolution of 120 μeV. Data on tip-sample Josephson contacts yield an even smaller feature size of 60 μeV, implying that the system operates close to the physical noise limit.
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Affiliation(s)
- Marcus Liebmann
- II. Institute of Physics B and JARA-FIT, RWTH Aachen University, 52074 Aachen, Germany
| | - Jan Raphael Bindel
- II. Institute of Physics B and JARA-FIT, RWTH Aachen University, 52074 Aachen, Germany
| | - Mike Pezzotta
- II. Institute of Physics B and JARA-FIT, RWTH Aachen University, 52074 Aachen, Germany
| | - Stefan Becker
- II. Institute of Physics B and JARA-FIT, RWTH Aachen University, 52074 Aachen, Germany
| | - Florian Muckel
- II. Institute of Physics B and JARA-FIT, RWTH Aachen University, 52074 Aachen, Germany
| | - Tjorven Johnsen
- II. Institute of Physics B and JARA-FIT, RWTH Aachen University, 52074 Aachen, Germany
| | - Christian Saunus
- II. Institute of Physics B and JARA-FIT, RWTH Aachen University, 52074 Aachen, Germany
| | - Christian R Ast
- Max-Planck-Institut für Festkörperforschung, 70569 Stuttgart, Germany
| | - Markus Morgenstern
- II. Institute of Physics B and JARA-FIT, RWTH Aachen University, 52074 Aachen, Germany
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