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Bermúdez-Perez JD, Herrera-Vasco E, Casas-Salgado J, Castelblanco HA, Vega-Bustos K, Cardenas-Chirivi G, Herrera-Sandoval OL, Suderow H, Giraldo-Gallo P, Galvis JA. High-resolution scanning tunneling microscope and its adaptation for local thermopower measurements in 2D materials. Ultramicroscopy 2024; 261:113963. [PMID: 38613941 DOI: 10.1016/j.ultramic.2024.113963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 03/05/2024] [Accepted: 04/01/2024] [Indexed: 04/15/2024]
Abstract
We present the design, fabrication and discuss the performance of a new combined high-resolution Scanning Tunneling and Thermopower Microscope (STM/SThEM). We also describe the development of the electronic control, the user interface, the vacuum system, and arrangements to reduce acoustical noise and vibrations. We demonstrate the microscope's performance with atomic-resolution topographic images of highly oriented pyrolytic graphite (HOPG) and local thermopower measurements in the semimetal Bi2Te3. Our system offers a tool to investigate the relationship between electronic structure and thermoelectric properties at the nanoscale.
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Affiliation(s)
- Jose D Bermúdez-Perez
- School of Engineering, Science and Technology, Universidad del Rosario, Bogotá 111711, Colombia; Facultad de Ingeniería y Ciencias Básicas, Universidad Central, Bogotá 110311, Colombia
| | - Edwin Herrera-Vasco
- Facultad de Ingeniería y Ciencias Básicas, Universidad Central, Bogotá 110311, Colombia; Laboratorio de Bajas Temperaturas y Altos Campos Magnéticos, Departamento de Física de la Materia Condensada, Instituto de Ciencia de Materiales Nicolás Cabrera, Condensed Matter Physics Center (IFIMAC), Facultad de Ciencias Universidad Autónoma de Madrid, 28049 Madrid, Spain; Departamento de Física Aplicada. Facultad de Ciencias. Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | - Javier Casas-Salgado
- Facultad de Ingeniería y Ciencias Básicas, Universidad Central, Bogotá 110311, Colombia
| | - Hector A Castelblanco
- Facultad de Ingeniería y Ciencias Básicas, Universidad Central, Bogotá 110311, Colombia
| | - Karen Vega-Bustos
- Department of Physics, Universidad de Los Andes, Bogotá 111711, Colombia
| | | | | | - Hermann Suderow
- Laboratorio de Bajas Temperaturas y Altos Campos Magnéticos, Departamento de Física de la Materia Condensada, Instituto de Ciencia de Materiales Nicolás Cabrera, Condensed Matter Physics Center (IFIMAC), Facultad de Ciencias Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | | | - Jose Augusto Galvis
- School of Engineering, Science and Technology, Universidad del Rosario, Bogotá 111711, Colombia.
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2
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Orfila G, Sanchez-Manzano D, Arora A, Cuellar F, Ruiz-Gómez S, Rodriguez-Corvillo S, López S, Peralta A, Carreira SJ, Gallego F, Tornos J, Rouco V, Riquelme JJ, Munuera C, Mompean FJ, Garcia-Hernandez M, Sefrioui Z, Villegas JE, Perez L, Rivera-Calzada A, Leon C, Valencia S, Santamaria J. Large Magnetoresistance of Isolated Domain Walls in La 2/3 Sr 1/3 MnO 3 Nanowires. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2211176. [PMID: 37046341 DOI: 10.1002/adma.202211176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 03/13/2023] [Indexed: 06/19/2023]
Abstract
Generation, manipulation, and sensing of magnetic domain walls are cornerstones in the design of efficient spintronic devices. Half-metals are amenable for this purpose as large low field magnetoresistance signals can be expected from spin accumulation at spin textures. Among half metals, La1- x Srx MnO3 (LSMO) manganites are considered as promising candidates for their robust half-metallic ground state, Curie temperature above room temperature (Tc = 360 K, for x = 1/3), and chemical stability. Yet domain wall magnetoresistance is poorly understood, with large discrepancies in the reported values and conflicting interpretation of experimental data due to the entanglement of various source of magnetoresistance, namely, spin accumulation, anisotropic magnetoresistance, and colossal magnetoresistance. In this work, the domain wall magnetoresistance is measured in LSMO cross-shape nanowires with single-domain walls nucleated across the current path. Magnetoresistance values above 10% are found to be originating at the spin accumulation caused by the mistracking effect of the spin texture of the domain wall by the conduction electrons. Fundamentally, this result shows the importance on non-adiabatic processes at spin textures despite the strong Hund coupling to the localized t2g electrons of the manganite. These large magnetoresistance values are high enough for encoding and reading magnetic bits in future oxide spintronic sensors.
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Affiliation(s)
- Gloria Orfila
- GFMC, Department Física de Materiales, Facultad de Física, Universidad Complutense, Madrid, 28040, Spain
| | | | - Ashima Arora
- Department Spin and Topology in Quantum Materials, Helmholtz-Zentrum Berlin für Materialien und Energie, 12489, Berlin, Germany
| | - Fabian Cuellar
- GFMC, Department Física de Materiales, Facultad de Física, Universidad Complutense, Madrid, 28040, Spain
| | - Sandra Ruiz-Gómez
- Physics of Quantum Materials, Max Planck Institute for Chemical Physics of Solids, 01187, Dresden, Germany
| | - Sara Rodriguez-Corvillo
- GFMC, Department Física de Materiales, Facultad de Física, Universidad Complutense, Madrid, 28040, Spain
| | - Sandra López
- GFMC, Department Física de Materiales, Facultad de Física, Universidad Complutense, Madrid, 28040, Spain
| | - Andrea Peralta
- GFMC, Department Física de Materiales, Facultad de Física, Universidad Complutense, Madrid, 28040, Spain
| | | | - Fernando Gallego
- GFMC, Department Física de Materiales, Facultad de Física, Universidad Complutense, Madrid, 28040, Spain
| | - Javier Tornos
- GFMC, Department Física de Materiales, Facultad de Física, Universidad Complutense, Madrid, 28040, Spain
| | - Victor Rouco
- GFMC, Department Física de Materiales, Facultad de Física, Universidad Complutense, Madrid, 28040, Spain
| | - Juan J Riquelme
- Departamento de Sistemas con baja dimensionalidad, Instituto de Ciencia de Materiales de Madrid (ICMM), CSIC, 28049, Cantoblanco, Spain
- Unidad Asociada UCM/CSIC, Laboratorio de Heteroestructuras con aplicación en spintrónica, 28140, Madrid, Spain
| | - Carmen Munuera
- Departamento de Sistemas con baja dimensionalidad, Instituto de Ciencia de Materiales de Madrid (ICMM), CSIC, 28049, Cantoblanco, Spain
- Unidad Asociada UCM/CSIC, Laboratorio de Heteroestructuras con aplicación en spintrónica, 28140, Madrid, Spain
| | - Federico J Mompean
- Departamento de Sistemas con baja dimensionalidad, Instituto de Ciencia de Materiales de Madrid (ICMM), CSIC, 28049, Cantoblanco, Spain
- Unidad Asociada UCM/CSIC, Laboratorio de Heteroestructuras con aplicación en spintrónica, 28140, Madrid, Spain
| | - Mar Garcia-Hernandez
- Departamento de Sistemas con baja dimensionalidad, Instituto de Ciencia de Materiales de Madrid (ICMM), CSIC, 28049, Cantoblanco, Spain
- Unidad Asociada UCM/CSIC, Laboratorio de Heteroestructuras con aplicación en spintrónica, 28140, Madrid, Spain
| | - Zouhair Sefrioui
- GFMC, Department Física de Materiales, Facultad de Física, Universidad Complutense, Madrid, 28040, Spain
- Unidad Asociada UCM/CSIC, Laboratorio de Heteroestructuras con aplicación en spintrónica, 28140, Madrid, Spain
| | | | - Lucas Perez
- GFMC, Department Física de Materiales, Facultad de Física, Universidad Complutense, Madrid, 28040, Spain
- Instituto Madrileño de Estudios Avanzados - IMDEA Nanoscience, 28049, Madrid, Spain
| | - Alberto Rivera-Calzada
- GFMC, Department Física de Materiales, Facultad de Física, Universidad Complutense, Madrid, 28040, Spain
- Unidad Asociada UCM/CSIC, Laboratorio de Heteroestructuras con aplicación en spintrónica, 28140, Madrid, Spain
| | - Carlos Leon
- GFMC, Department Física de Materiales, Facultad de Física, Universidad Complutense, Madrid, 28040, Spain
- Unidad Asociada UCM/CSIC, Laboratorio de Heteroestructuras con aplicación en spintrónica, 28140, Madrid, Spain
| | - Sergio Valencia
- Department Spin and Topology in Quantum Materials, Helmholtz-Zentrum Berlin für Materialien und Energie, 12489, Berlin, Germany
| | - Jacobo Santamaria
- GFMC, Department Física de Materiales, Facultad de Física, Universidad Complutense, Madrid, 28040, Spain
- Unidad Asociada UCM/CSIC, Laboratorio de Heteroestructuras con aplicación en spintrónica, 28140, Madrid, Spain
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3
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Zhou L, He Q, Que X, Rost AW, Takagi H. A spectroscopic-imaging scanning tunneling microscope in vector magnetic field. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2023; 94:033704. [PMID: 37012779 DOI: 10.1063/5.0131532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 02/15/2023] [Indexed: 06/19/2023]
Abstract
Cryogenic scanning tunneling microscopy and spectroscopy (STM/STS) performed in a high vector magnetic field provide unique possibilities for imaging surface magnetic structures and anisotropic superconductivity and exploring spin physics in quantum materials with atomic precision. Here, we describe the design, construction, and performance of a low-temperature, ultra-high-vacuum (UHV) spectroscopic-imaging STM equipped with a vector magnet capable of applying a field of up to 3 T in any direction with respect to the sample surface. The STM head is housed in a fully bakeable UHV compatible cryogenic insert and is operational over variable temperatures ranging from ∼300 down to 1.5 K. The insert can be easily upgraded using our home-designed 3He refrigerator. In addition to layered compounds, which can be cleaved at a temperature of either ∼300, ∼77, or ∼4.2 K to expose an atomically flat surface, thin films can also be studied by directly transferring using a UHV suitcase from our oxide thin-film laboratory. Samples can be treated further with a heater and a liquid helium/nitrogen cooling stage on a three-axis manipulator. The STM tips can be treated in vacuo by e-beam bombardment and ion sputtering. We demonstrate the successful operation of the STM with varying the magnetic field direction. Our facility provides a way to study materials in which magnetic anisotropy is a key factor in determining the electronic properties such as in topological semimetals and superconductors.
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Affiliation(s)
- Lihui Zhou
- Max Planck Institute for Solid State Research, Heisenbergstrasse 1, Stuttgart 70569, Germany
| | - Qingyu He
- Max Planck Institute for Solid State Research, Heisenbergstrasse 1, Stuttgart 70569, Germany
| | - Xinglu Que
- Max Planck Institute for Solid State Research, Heisenbergstrasse 1, Stuttgart 70569, Germany
| | - Andreas W Rost
- Max Planck Institute for Solid State Research, Heisenbergstrasse 1, Stuttgart 70569, Germany
| | - Hide Takagi
- Max Planck Institute for Solid State Research, Heisenbergstrasse 1, Stuttgart 70569, Germany
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4
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Xiang K, Hou Y, Wang J, Zhang J, Feng Q, Wang Z, Meng W, Lu Q, Lu Y. A piezoelectric rotatable magnetic force microscope system in a 10 T cryogen-free superconducting magnet. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2022; 93:093706. [PMID: 36182484 DOI: 10.1063/5.0100662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 08/19/2022] [Indexed: 06/16/2023]
Abstract
We constructed a piezoelectric rotatable magnetic force microscope (MFM) that works in a 10 T cryogen-free superconducting magnet. The piezoelectric tube is deformed tangentially and drives a bearing under the inertial drive principle so the MFM head can obtain rotary movement. Due to the novel piezoelectric design, the MFM can be hung underneath the heat sink via a soft spring, and it can be rotated in a cryogen-free superconducting magnet so that the direction of the magnetic field can be changed from 0° to 90° continuously. The system functions in magnetic fields of up to 10 T in any direction relative to the tip-sample geometry. This is the first piezoelectric rotatable MFM ever reported. Using this homemade rotatable MFM, we imaged the structure of magnetic tracks on a commercial videotape. When the magnetic field angle changes from 0° to 90°, the magnetic moments on the tape and probe tip also rotate. A magnetic field strength of 0.8 T parallel to the sample surface is required to fully rotate the magnetic moment of the tip we used, but 0.8 T is not enough to fully rotate the magnetic moment of the sample. The piezoelectric rotatable MFM is expected to be widely used to study the anisotropy of magnetic materials due to its superiority in obtaining the same high field in and out of plane (compared with a vector magnet) as well as in maintaining the same scan area precisely (compared with a mechanical rotatable MFM, especially for atomic-scale scan areas).
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Affiliation(s)
- Kui Xiang
- High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Science, Hefei, Anhui 230031, China
| | - Yubin Hou
- High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Science, Hefei, Anhui 230031, China
| | - Jihao Wang
- High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Science, Hefei, Anhui 230031, China
| | - Jing Zhang
- High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Science, Hefei, Anhui 230031, China
| | - Qiyuan Feng
- High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Science, Hefei, Anhui 230031, China
| | - Ze Wang
- High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Science, Hefei, Anhui 230031, China
| | - Wenjie Meng
- High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Science, Hefei, Anhui 230031, China
| | - Qingyou Lu
- High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Science, Hefei, Anhui 230031, China
| | - Yalin Lu
- University of Science and Technology of China, Hefei, Anhui 230026, China
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5
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Martín-Vega F, Barrena V, Sánchez-Barquilla R, Fernández-Lomana M, Benito Llorens J, Wu B, Fente A, Perconte Duplain D, Horcas I, López R, Blanco J, Higuera JA, Mañas-Valero S, Jo NH, Schmidt J, Canfield PC, Rubio-Bollinger G, Rodrigo JG, Herrera E, Guillamón I, Suderow H. Simplified feedback control system for scanning tunneling microscopy. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:103705. [PMID: 34717388 DOI: 10.1063/5.0064511] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Accepted: 09/18/2021] [Indexed: 06/13/2023]
Abstract
A Scanning Tunneling Microscope (STM) is one of the most important scanning probe tools available to study and manipulate matter at the nanoscale. In a STM, a tip is scanned on top of a surface with a separation of a few Å. Often, the tunneling current between the tip and the sample is maintained constant by modifying the distance between the tip apex and the surface through a feedback mechanism acting on a piezoelectric transducer. This produces very detailed images of the electronic properties of the surface. The feedback mechanism is nearly always made using a digital processing circuit separate from the user computer. Here, we discuss another approach using a computer and data acquisition through the universal serial bus port. We find that it allows successful ultralow noise studies of surfaces at cryogenic temperatures. We show results on different compounds including a type II Weyl semimetal (WTe2), a quasi-two-dimensional dichalcogenide superconductor (2H-NbSe2), a magnetic Weyl semimetal (Co3Sn2S2), and an iron pnictide superconductor (FeSe).
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Affiliation(s)
- 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
| | - Víctor Barrena
- 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
| | - 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
| | - José Benito Llorens
- 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
| | - Antón Fente
- 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
| | - David Perconte Duplain
- 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
| | - Ignacio Horcas
- Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | - Raquel López
- SEGAINVEX, Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | - Javier Blanco
- SEGAINVEX, Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | | | - Samuel Mañas-Valero
- Instituto de Ciencia Molecular (ICMol), Universidad de Valencia, Catedrático José Beltrán 2, 46980 Paterna, Spain
| | - Na Hyun Jo
- Ames Laboratory, U.S. DOE, Iowa State University, Ames, Iowa 50011, USA
| | - Juan Schmidt
- Ames Laboratory, U.S. DOE, Iowa State University, Ames, Iowa 50011, USA
| | - Paul C Canfield
- Ames Laboratory, U.S. DOE, Iowa State University, Ames, Iowa 50011, USA
| | - Gabino Rubio-Bollinger
- 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 Gabriel Rodrigo
- 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
| | - 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
| | - 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
| | - 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
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6
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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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7
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Guo T, Wang J, Meng W, Zhang J, Feng Q, Wang Z, Jin F, Wu W, Lu Q, Hou Y, Lu Q. A mechanical rotatable magnetic force microscope operated in a 7 T superconducting magnet. Ultramicroscopy 2020; 217:113071. [PMID: 32717554 DOI: 10.1016/j.ultramic.2020.113071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 05/17/2020] [Accepted: 07/09/2020] [Indexed: 10/23/2022]
Abstract
We present a mechanical rotatable magnetic force microscope (MFM) with precise angle control that can be operated in a 7 T superconducting magnet. An inertial piezoelectric motor called a SpiderDrive was used for the coarse approach because of its high compactness, high rigidity, and small size. Due to the mechanical rotation design, the MFM head can be rotated in a 7 T superconducting magnet with a bore size of 89 mm so that the direction of the magnetic field can be changed from 0° to 90° continuously. The highest in-plane magnetic field strength tested was 7 T. This is the first rotatable MFM ever reported. Using the homemade rotatable MFM, we investigated a 40 nm thick La0.67Ca0.33MnO3 (LCMO) thin film on NdGaO3 (100) substrate with anisotropy, determining that the charge-ordering insulating (COI) phase of the LCMO disappears as the direction of the magnetic field changed from 0° to 90°. Furthermore, the ferromagnetic pattern, appearing as bright and dark contrasts and similar to that formed by the S and N of a magnet, was seen parallel to the direction of the magnetic field. The rotatable MFM in this paper is expected to be widely used in studying the anisotropy of magnetic materials.
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Affiliation(s)
- Tengfei Guo
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory and High Magnetic Field laboratory of Anhui Province, Chinese Academy of Sciences, Hefei, AnHui 230031, China; Hefei National Laboratory for Physical Sciences at Microscale and Anhui Laboratory of Advanced Photon Science and Technology, University of Science and Technology of China, Hefei, AnHui 230026, China
| | - Jihao Wang
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory and High Magnetic Field laboratory of Anhui Province, Chinese Academy of Sciences, Hefei, AnHui 230031, China
| | - Wenjie Meng
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory and High Magnetic Field laboratory of Anhui Province, Chinese Academy of Sciences, Hefei, AnHui 230031, China
| | - Jing Zhang
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory and High Magnetic Field laboratory of Anhui Province, Chinese Academy of Sciences, Hefei, AnHui 230031, China
| | - Qiyuan Feng
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory and High Magnetic Field laboratory of Anhui Province, Chinese Academy of Sciences, Hefei, AnHui 230031, China
| | - Ze Wang
- Hefei National Laboratory for Physical Sciences at Microscale and Anhui Laboratory of Advanced Photon Science and Technology, University of Science and Technology of China, Hefei, AnHui 230026, China
| | - Feng Jin
- Hefei National Laboratory for Physical Sciences at Microscale and Anhui Laboratory of Advanced Photon Science and Technology, University of Science and Technology of China, Hefei, AnHui 230026, China
| | - Wenbin Wu
- Hefei National Laboratory for Physical Sciences at Microscale and Anhui Laboratory of Advanced Photon Science and Technology, University of Science and Technology of China, Hefei, AnHui 230026, China
| | - Qingyi Lu
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, JiangSu 210093, China; State Key Laboratory of Coordination Chemistry, School of Chemical Engineering. Nanjing National Laboratory of Microstructures, Nanjing University, Nanjing JiangSu 210093, China
| | - Yubin Hou
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory and High Magnetic Field laboratory of Anhui Province, Chinese Academy of Sciences, Hefei, AnHui 230031, China.
| | - Qingyou Lu
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory and High Magnetic Field laboratory of Anhui Province, Chinese Academy of Sciences, Hefei, AnHui 230031, China; Hefei National Laboratory for Physical Sciences at Microscale and Anhui Laboratory of Advanced Photon Science and Technology, University of Science and Technology of China, Hefei, AnHui 230026, China; Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, JiangSu 210093, China; Hefei Science Center Chinese Academy of Sciences, Hefei 230031, China.
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8
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Wang P, Huang K, Sun J, Hu J, Fu H, Lin X. Piezo-driven sample rotation system with ultra-low electron temperature. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2019; 90:023905. [PMID: 30831686 DOI: 10.1063/1.5083994] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 01/19/2019] [Indexed: 06/09/2023]
Abstract
Piezo-driven rotator is convenient for tilted magnetic field experiments due to its precise angle control. However, the rotator itself and the sample mounted on it are difficult to be cooled down because of extra heat leaks and presumably bad thermal contacts from the piezo. Here, we report a piezo-driven sample rotation system designed for ultra-low temperature environment. The sample, as well as the rotating sample holder, can be cooled to as low as 25 mK by customized thermal links and thermal contacts. More importantly, the electron temperature in the electrical transport measurements can also be cooled down to 25 mK with the help of home-made filters. To demonstrate the application of our rotation system at ultra-low electron temperature, a measurement revealing tilt-induced localization and delocalization in the second Landau level of two-dimensional electron gas is provided.
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Affiliation(s)
- Pengjie Wang
- International Center for Quantum Materials, Peking University, Beijing 100871, China
| | - Ke Huang
- International Center for Quantum Materials, Peking University, Beijing 100871, China
| | - Jian Sun
- International Center for Quantum Materials, Peking University, Beijing 100871, China
| | - Jingjin Hu
- International Center for Quantum Materials, Peking University, Beijing 100871, China
| | - Hailong Fu
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Xi Lin
- International Center for Quantum Materials, Peking University, Beijing 100871, China
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9
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Rossi L, Gerritsen JW, Nelemans L, Khajetoorians AA, Bryant B. An ultra-compact low temperature scanning probe microscope for magnetic fields above 30 T. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:113706. [PMID: 30501346 DOI: 10.1063/1.5046578] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 10/18/2018] [Indexed: 06/09/2023]
Abstract
We present the design of a highly compact high field scanning probe microscope (HF-SPM) for operation at cryogenic temperatures in an extremely high magnetic field, provided by a water-cooled Bitter magnet able to reach 38 T. The HF-SPM is 14 mm in diameter: an Attocube nano-positioner controls the coarse approach of a piezoresistive atomic force microscopy cantilever to a scanned sample. The Bitter magnet constitutes an extreme environment for scanning probe microscopy (SPM) due to the high level of vibrational noise; the Bitter magnet noise at frequencies up to 300 kHz is characterized, and noise mitigation methods are described. The performance of the HF-SPM is demonstrated by topographic imaging and noise measurements at up to 30 T. Additionally, the use of the SPM as a three-dimensional dilatometer for magnetostriction measurements is demonstrated via measurements on a magnetically frustrated spinel sample.
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Affiliation(s)
- L Rossi
- High Field Magnet Laboratory (HFML-EMFL), Radboud University, Nijmegen, The Netherlands
| | - J W Gerritsen
- Institute of Molecules and Materials, Radboud University, Nijmegen, The Netherlands
| | - L Nelemans
- High Field Magnet Laboratory (HFML-EMFL), Radboud University, Nijmegen, The Netherlands
| | - A A Khajetoorians
- Institute of Molecules and Materials, Radboud University, Nijmegen, The Netherlands
| | - B Bryant
- High Field Magnet Laboratory (HFML-EMFL), Radboud University, Nijmegen, The Netherlands
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10
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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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11
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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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12
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Trainer C, Yim CM, McLaren M, Wahl P. Cryogenic STM in 3D vector magnetic fields realized through a rotatable insert. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2017; 88:093705. [PMID: 28964195 DOI: 10.1063/1.4995688] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 09/07/2017] [Indexed: 06/07/2023]
Abstract
Spin-polarized scanning tunneling microscopy (SP-STM) performed in vector magnetic fields promises atomic scale imaging of magnetic structure, providing complete information on the local spin texture of a sample in three dimensions. Here, we have designed and constructed a turntable system for a low temperature STM which in combination with a 2D vector magnet provides magnetic fields of up to 5 T in any direction relative to the tip-sample geometry. This enables STM imaging and spectroscopy to be performed at the same atomic-scale location and field-of-view on the sample, and most importantly, without experiencing any change on the tip apex before and after field switching. Combined with a ferromagnetic tip, this enables us to study the magnetization of complex magnetic orders in all three spatial directions.
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Affiliation(s)
- C Trainer
- SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS, United Kingdom
| | - C M Yim
- SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS, United Kingdom
| | - M McLaren
- SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS, United Kingdom
| | - P Wahl
- SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS, United Kingdom
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13
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Rocci M, Azpeitia J, Trastoy J, Perez-Muñoz A, Cabero M, Luccas RF, Munuera C, Mompean FJ, Garcia-Hernandez M, Bouzehouane K, Sefrioui Z, Leon C, Rivera-Calzada A, Villegas JE, Santamaria J. Proximity Driven Commensurate Pinning in YBa2Cu3O7 through All-Oxide Magnetic Nanostructures. NANO LETTERS 2015; 15:7526-7531. [PMID: 26441137 DOI: 10.1021/acs.nanolett.5b03261] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The design of artificial vortex pinning landscapes is a major goal toward large scale applications of cuprate superconductors. Although disordered nanometric inclusions have shown to modify their vortex phase diagram and to produce enhancements of the critical current ( MacManus-Driscoll , J. L. ; Foltyn , S. R. ; Jia , Q. X. ; Wang , H. ; Serquis , A. ; Civale , L. ; Maiorov , B. ; Hawley , M. E. ; Maley , M. P. ; Peterson , D. E. Nat. Mater. 2004 , 3 , 439 - 443 and Yamada , Y. ; Takahashi , K. ; Kobayashi , H. ; Konishi , M. ; Watanabe , T. ; Ibi , A. ; Muroga , T. ; Miyata , S. ; Kato , T. ; Hirayama , T. ; Shiohara , Y. Appl. Phys. Lett. 2005 , 87 , 1 - 3 ), the effect of ordered oxide nanostructures remains essentially unexplored. This is due to the very small nanostructure size imposed by the short coherence length, and to the technological difficulties in the nanofabrication process. Yet, the novel phenomena occurring at oxide interfaces open a wide spectrum of technological opportunities to interplay with the superconductivity in cuprates. Here, we show that the unusual long-range suppression of the superconductivity occurring at the interface between manganites and cuprates affects vortex nucleation and provides a novel vortex pinning mechanism. In particular, we show evidence of commensurate pinning in YBCO films with ordered arrays of LCMO ferromagnetic nanodots. Vortex pinning results from the proximity induced reduction of the condensation energy at the vicinity of the magnetic nanodots, and yields an enhanced friction between the nanodot array and the moving vortex lattice in the liquid phase. This result shows that all-oxide ordered nanostructures constitute a powerful, new route for the artificial manipulation of vortex matter in cuprates.
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Affiliation(s)
- M Rocci
- GFMC, Dpto. Fisica Aplicada III, Univ. Complutense Madrid , 28040 Madrid, Spain
- Unidad Asociada Laboratorio de Heteroestructuras con Aplicación en Espintrónica" UCM-CSIC , 28049 Madrid, Spain
| | - J Azpeitia
- Instituto de Ciencia de Materiales de Madrid , 28049 Madrid, Spain
- Unidad Asociada Laboratorio de Heteroestructuras con Aplicación en Espintrónica" UCM-CSIC , 28049 Madrid, Spain
| | - J Trastoy
- Unité Mixte de Physique, CNRS, Thales, Univ. Paris-Sud, Université , Paris-Saclay, 91767, Palaiseau, France
- Université Paris Sud , 91407 Orsay, France
| | - A Perez-Muñoz
- GFMC, Dpto. Fisica Aplicada III, Univ. Complutense Madrid , 28040 Madrid, Spain
- Unidad Asociada Laboratorio de Heteroestructuras con Aplicación en Espintrónica" UCM-CSIC , 28049 Madrid, Spain
| | - M Cabero
- GFMC, Dpto. Fisica Aplicada III, Univ. Complutense Madrid , 28040 Madrid, Spain
- Unidad Asociada Laboratorio de Heteroestructuras con Aplicación en Espintrónica" UCM-CSIC , 28049 Madrid, Spain
| | - R F Luccas
- Instituto de Ciencia de Materiales de Madrid , 28049 Madrid, Spain
- Unidad Asociada Laboratorio de Heteroestructuras con Aplicación en Espintrónica" UCM-CSIC , 28049 Madrid, Spain
| | - C Munuera
- Instituto de Ciencia de Materiales de Madrid , 28049 Madrid, Spain
- Unidad Asociada Laboratorio de Heteroestructuras con Aplicación en Espintrónica" UCM-CSIC , 28049 Madrid, Spain
| | - F J Mompean
- Instituto de Ciencia de Materiales de Madrid , 28049 Madrid, Spain
- Unidad Asociada Laboratorio de Heteroestructuras con Aplicación en Espintrónica" UCM-CSIC , 28049 Madrid, Spain
| | - M Garcia-Hernandez
- Instituto de Ciencia de Materiales de Madrid , 28049 Madrid, Spain
- Unidad Asociada Laboratorio de Heteroestructuras con Aplicación en Espintrónica" UCM-CSIC , 28049 Madrid, Spain
| | - K Bouzehouane
- Unité Mixte de Physique, CNRS, Thales, Univ. Paris-Sud, Université , Paris-Saclay, 91767, Palaiseau, France
- Université Paris Sud , 91407 Orsay, France
| | - Z Sefrioui
- GFMC, Dpto. Fisica Aplicada III, Univ. Complutense Madrid , 28040 Madrid, Spain
- Unidad Asociada Laboratorio de Heteroestructuras con Aplicación en Espintrónica" UCM-CSIC , 28049 Madrid, Spain
| | - C Leon
- GFMC, Dpto. Fisica Aplicada III, Univ. Complutense Madrid , 28040 Madrid, Spain
- Unidad Asociada Laboratorio de Heteroestructuras con Aplicación en Espintrónica" UCM-CSIC , 28049 Madrid, Spain
| | - A Rivera-Calzada
- GFMC, Dpto. Fisica Aplicada III, Univ. Complutense Madrid , 28040 Madrid, Spain
- Unidad Asociada Laboratorio de Heteroestructuras con Aplicación en Espintrónica" UCM-CSIC , 28049 Madrid, Spain
| | - J E Villegas
- Unité Mixte de Physique, CNRS, Thales, Univ. Paris-Sud, Université , Paris-Saclay, 91767, Palaiseau, France
- Université Paris Sud , 91407 Orsay, France
| | - J Santamaria
- GFMC, Dpto. Fisica Aplicada III, Univ. Complutense Madrid , 28040 Madrid, Spain
- Unidad Asociada Laboratorio de Heteroestructuras con Aplicación en Espintrónica" UCM-CSIC , 28049 Madrid, Spain
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