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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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Zhao K, Zhang J, Meng W, Zheng S, Wang J, Feng Q, Wang Z, Hou Y, Lu Q, Lu Y. Cryogenic spectroscopic imaging scanning tunnelling microscope in a water-cooled magnet down to 1.7 K. Ultramicroscopy 2023; 253:113773. [PMID: 37315346 DOI: 10.1016/j.ultramic.2023.113773] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 04/19/2023] [Accepted: 05/30/2023] [Indexed: 06/16/2023]
Abstract
Spectroscopic-imaging scanning tunnelling microscope (SI-STM) in a water-cooled magnet (WM) at low temperature has long been desirable in the condensed matter physics area since it is crucial for addressing various scientific problems, such as the behaviour of Cooper electrons crossing Hc2 in a high-temperature superconductor. Here we report on the construction and performance of the first atomically resolved cryogenic SI-STM in a WM. It operates at low temperatures of down to 1.7 K and in magnetic fields of up to 22 T (the WM's upper safety limit). The WM-SI-STM unit features a high-stiffness sapphire-based frame with the lowest eigenfrequency being 16 kHz. A slender piezoelectric scan tube (PST) is coaxially embedded in and glued to the frame. A well-polished zirconia shaft is spring-clamped onto the gold-coated inner wall of the PST to serve both the stepper and the scanner. The microscope unit as a whole is elastically suspended in a tubular sample space inside a 1K-cryostat by a two-stage internal passive vibrational reduction system, achieving a base temperature below 2 K in a static exchange gas. We demonstrate the SI-STM by imaging TaS2 at 50 K and FeSe at 1.7 K. Detecting the well-defined superconducting gap of FeSe, an iron-based superconductor, at variable magnetic fields demonstrates the device's spectroscopic imaging capability. The maximum noise intensity at the typical frequency is 3 pA per square root Hz at 22 T, which is only slightly worse than at 0 T, indicating the insensitivity of the STM to harsh conditions. In addition, our work shows the potential of SI-STMs for use in a WM and hybrid magnet with a 50 mm-bore size where high fields can be generated.
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Affiliation(s)
- Kesen Zhao
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory of the Chinese Academy of Sciences, Hefei Institudes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui 230031, People's Republic of China; University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China; The High Magnetic Field Laboratory of Anhui Province, Hefei, Anhui 230031, People's Republic of China
| | - Jing Zhang
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory of the Chinese Academy of Sciences, Hefei Institudes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui 230031, People's Republic of China; The High Magnetic Field Laboratory of Anhui Province, Hefei, Anhui 230031, People's Republic of China
| | - Wenjie Meng
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory of the Chinese Academy of Sciences, Hefei Institudes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui 230031, People's Republic of China; The High Magnetic Field Laboratory of Anhui Province, Hefei, Anhui 230031, People's Republic of China.
| | - Shaofeng Zheng
- University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China; The High Magnetic Field Laboratory of Anhui Province, Hefei, Anhui 230031, People's Republic of China
| | - Jihao Wang
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory of the Chinese Academy of Sciences, Hefei Institudes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui 230031, People's Republic of China; The High Magnetic Field Laboratory of Anhui Province, Hefei, Anhui 230031, People's Republic of China
| | - Qiyuan Feng
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory of the Chinese Academy of Sciences, Hefei Institudes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui 230031, People's Republic of China; The High Magnetic Field Laboratory of Anhui Province, Hefei, Anhui 230031, People's Republic of China
| | - Ze Wang
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory of the Chinese Academy of Sciences, Hefei Institudes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui 230031, People's Republic of China; The High Magnetic Field Laboratory of Anhui Province, Hefei, Anhui 230031, People's Republic of China
| | - Yubin Hou
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory of the Chinese Academy of Sciences, Hefei Institudes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui 230031, People's Republic of China; The High Magnetic Field Laboratory of Anhui Province, Hefei, Anhui 230031, People's Republic of China.
| | - Qingyou Lu
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory of the Chinese Academy of Sciences, Hefei Institudes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui 230031, People's Republic of China; University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China; The High Magnetic Field Laboratory of Anhui Province, Hefei, Anhui 230031, People's Republic of China; Anhui Laboratory of Advanced Photon Science and Technology, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China; Hefei Science Center Chinese Academy of Sciences, Hefei 230031, People's Republic of China.
| | - Yalin Lu
- University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China; Anhui Laboratory of Advanced Photon Science and Technology, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
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3
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Ahn T, Song S, Ham U, Kim TH. Systematic investigation of wear-induced cold welding in ultrahigh vacuum piezoelectric motors with non-metallic coatings. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2023; 94:063702. [PMID: 37862495 DOI: 10.1063/5.0147344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Accepted: 05/25/2023] [Indexed: 10/22/2023]
Abstract
Piezoelectric motors are widely used in various applications where both precision positioning and miniaturization are required. Inertial or quasi-static motors are commonly employed because of their high accuracy, which demands consistent sliding friction between moving sliders and their static counterparts for reliable operation. In general, slider wear is unavoidable after long-term use. This wear can often lead to more serious cold welding in vacuum, which is also referred to as friction welding induced by direct contact between similar metal surfaces. Non-metallic coatings can prevent such unwanted cold welding in ultrahigh vacuum (UHV) applications. However, the practical reliability of available coatings under UHV conditions still remains to be elucidated. Here, we systematically investigate the practical reliability of commonly used, UHV-compatible lubricant coatings for piezoelectric motors in vacuum. We demonstrate that polytetrafluoroethylene (PTFE) shows the most reliable long-term operation in vacuum, while other coatings eventually lead to wear-induced cold welding and motor failure. Our findings provide a simple and effective method to improve the long-term performance of UHV piezoelectric motors by coating the slider surface with PTFE.
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Affiliation(s)
- Taemin Ahn
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang 37673, South Korea
| | - Sungmin Song
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang 37673, South Korea
| | - Ungdon Ham
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science (IBS), Pohang 37673, South Korea
| | - Tae-Hwan Kim
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang 37673, South Korea
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Herrera E, Guillamón I, Barrena V, Herrera WJ, Galvis JA, Yeyati AL, Rusz J, Oppeneer PM, Knebel G, Brison JP, Flouquet J, Aoki D, Suderow H. Quantum-well states at the surface of a heavy-fermion superconductor. Nature 2023; 616:465-469. [PMID: 36949204 PMCID: PMC10115632 DOI: 10.1038/s41586-023-05830-1] [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: 06/19/2022] [Accepted: 02/13/2023] [Indexed: 03/24/2023]
Abstract
Two-dimensional electronic states at surfaces are often observed in simple wide-band metals such as Cu or Ag (refs. 1-4). Confinement by closed geometries at the nanometre scale, such as surface terraces, leads to quantized energy levels formed from the surface band, in stark contrast to the continuous energy dependence of bulk electron bands2,5-10. Their energy-level separation is typically hundreds of meV (refs. 3,6,11). In a distinct class of materials, strong electronic correlations lead to so-called heavy fermions with a strongly reduced bandwidth and exotic bulk ground states12,13. Quantum-well states in two-dimensional heavy fermions (2DHFs) remain, however, notoriously difficult to observe because of their tiny energy separation. Here we use millikelvin scanning tunnelling microscopy (STM) to study atomically flat terraces on U-terminated surfaces of the heavy-fermion superconductor URu2Si2, which exhibits a mysterious hidden-order (HO) state below 17.5 K (ref. 14). We observe 2DHFs made of 5f electrons with an effective mass 17 times the free electron mass. The 2DHFs form quantized states separated by a fraction of a meV and their level width is set by the interaction with correlated bulk states. Edge states on steps between terraces appear along one of the two in-plane directions, suggesting electronic symmetry breaking at the surface. Our results propose a new route to realize quantum-well states in strongly correlated quantum materials and to explore how these connect to the electronic environment.
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Affiliation(s)
- Edwin Herrera
- Facultad de Ingeniería y Ciencias Básicas, Universidad Central, Bogotá, Colombia.
- Departamento de Física, Universidad Nacional de Colombia, Bogotá, Colombia.
- 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, 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, 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, Madrid, Spain
| | - William J Herrera
- Departamento de Física, Universidad Nacional de Colombia, Bogotá, Colombia
| | - Jose Augusto Galvis
- Facultad de Ingeniería y Ciencias Básicas, Universidad Central, Bogotá, Colombia
- School of Engineering, Science and Technology, Universidad del Rosario, Bogotá, Colombia
| | - Alfredo Levy Yeyati
- Departamento de Física Teórica de la Materia Condensada, Instituto Nicolás Cabrera and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, Madrid, Spain
| | - Ján Rusz
- Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden
| | - Peter M Oppeneer
- Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden
| | - Georg Knebel
- University Grenoble Alpes, CEA, Grenoble-INP, IRIG, PHELIQS, Grenoble, France
| | - Jean Pascal Brison
- University Grenoble Alpes, CEA, Grenoble-INP, IRIG, PHELIQS, Grenoble, France
| | - Jacques Flouquet
- University Grenoble Alpes, CEA, Grenoble-INP, IRIG, PHELIQS, Grenoble, France
| | - Dai Aoki
- Institute for Materials Research (IMR), Tohoku University, Oarai, Japan
| | - 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, Madrid, Spain.
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