1
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Niu J, Bastiaans KM, Ge JF, Tomar R, Jesudasan J, Raychaudhuri P, Karrer M, Kleiner R, Koelle D, Barbier A, Driessen EFC, Blanter YM, Allan MP. Why Shot Noise Does Not Generally Detect Pairing in Mesoscopic Superconducting Tunnel Junctions. PHYSICAL REVIEW LETTERS 2024; 132:076001. [PMID: 38427861 DOI: 10.1103/physrevlett.132.076001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 10/13/2023] [Accepted: 12/01/2023] [Indexed: 03/03/2024]
Abstract
The shot noise in tunneling experiments reflects the Poissonian nature of the tunneling process. The shot-noise power is proportional to both the magnitude of the current and the effective charge of the carrier. Shot-noise spectroscopy thus enables us, in principle, to determine the effective charge q of the charge carriers of that tunnel. This can be used to detect electron pairing in superconductors: In the normal state, the noise corresponds to single electron tunneling (q=1e), while in the paired state, the noise corresponds to q=2e. Here, we use a newly developed amplifier to reveal that in typical mesoscopic superconducting junctions, the shot noise does not reflect the signatures of pairing and instead stays at a level corresponding to q=1e. We show that transparency can control the shot noise, and this q=1e is due to the large number of tunneling channels with each having very low transparency. Our results indicate that in typical mesoscopic superconducting junctions, one should expect q=1e noise and lead to design guidelines for junctions that allow the detection of electron pairing.
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Affiliation(s)
- Jiasen Niu
- Leiden Institute of Physics, Leiden University, 2333 CA Leiden, The Netherlands
| | - Koen M Bastiaans
- Department of Quantum Nanoscience, Kavli Institute of Nanoscience, Delft University of Technology, 2628 CJ Delft, The Netherlands
| | - Jian-Feng Ge
- Leiden Institute of Physics, Leiden University, 2333 CA Leiden, The Netherlands
| | - Ruchi Tomar
- Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India
| | - John Jesudasan
- Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India
| | - Pratap Raychaudhuri
- Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India
| | - Max Karrer
- Physikalisches Institut, Center for Quantum Science (CQ) and LISA+, Universität Tübingen, D-72076 Tübingen, Germany
| | - Reinhold Kleiner
- Physikalisches Institut, Center for Quantum Science (CQ) and LISA+, Universität Tübingen, D-72076 Tübingen, Germany
| | - Dieter Koelle
- Physikalisches Institut, Center for Quantum Science (CQ) and LISA+, Universität Tübingen, D-72076 Tübingen, Germany
| | - Arnaud Barbier
- Institut de Radioastronomie Millimétrique (IRAM), Domaine Universitaire de Grenoble, 38400 Saint-Martin-d'Hères, France
| | - Eduard F C Driessen
- Institut de Radioastronomie Millimétrique (IRAM), Domaine Universitaire de Grenoble, 38400 Saint-Martin-d'Hères, France
| | - Yaroslav M Blanter
- Department of Quantum Nanoscience, Kavli Institute of Nanoscience, Delft University of Technology, 2628 CJ Delft, The Netherlands
| | - Milan P Allan
- Leiden Institute of Physics, Leiden University, 2333 CA Leiden, The Netherlands
- Fakultät für Physik, Ludwig-Maximilians-Universität, Schellingstrasse 4, München 80799, Germany
- Munich Center for Quantum Science and Technology (MCQST), München, Germany
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2
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Liang YX. Low-noise large-bandwidth transimpedance amplifier for measuring scanning tunneling shot noise spectra in cryogenic STM and its applications. Ultramicroscopy 2022; 234:113466. [PMID: 35121281 DOI: 10.1016/j.ultramic.2022.113466] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 09/21/2021] [Accepted: 01/10/2022] [Indexed: 11/28/2022]
Abstract
Shot noise is a powerful tool to study quantum systems. In this work, a design of transimpedance amplifier (TIA) for a cryogenic scanning tunneling microscope (CryoSTM) is proposed to meet the requirements of the shot noise measurements for quantum systems. In the TIA, the preamplifier is made of the low-noise low-power cryogenic high electron mobility transistors. With the high transimpedance gain of 1 GΩ, the bandwidth of the proposed TIA is larger than 300 kHz. In the CryoSTM, the TIA with the tip-sample component is called as CryoSTM-TIA. The bandwidth of the proposed CryoSTM-TIA is still larger than 300 kHz. Its equivalent input noise current power spectral density is less than 30(fA)2/Hz at 100 kHz. It is detailed, for quantum systems, by using the CryoSTM-TIA, how to measure scanning tunneling current spectra, scanning tunneling differential conductance spectra, and scanning tunneling noise current power spectra, in atomic scale, and then extract their scanning tunneling shot noise spectra. Thus, it is possible to study novel quantum phenomena in various quantum systems by measuring shot noise with the CryoSTM-TIA, such as the Andreev reflection in atomic scale, the Kondo effect in a single molecular magnet, and the existence of Majorana bound states, etc.
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Affiliation(s)
- Ying-Xin Liang
- Anyang Normal Univ, Sch Phys & Elect Engn, No. 436, Xiange Avenue, Anyang 455000, Henan, China.
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3
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Tamir I, Caspari V, Rolf D, Lotze C, Franke KJ. Shot-noise measurements of single-atom junctions using a scanning tunneling microscope. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2022; 93:023702. [PMID: 35232162 DOI: 10.1063/5.0078917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 01/26/2022] [Indexed: 06/14/2023]
Abstract
Current fluctuations related to the discreteness of charge passing through small constrictions are termed shot noise. This unavoidable noise provides both advantages-being a direct measurement of the transmitted particles' charge-and disadvantages-a main noise source in nanoscale devices operating at low temperature. While better understanding of shot noise is desired, the technical difficulties in measuring it result in relatively few experimental works, especially in single-atom structures. Here, we describe a local shot-noise measurement apparatus and demonstrate successful noise measurements through single-atom junctions. Our apparatus, based on a scanning tunneling microscope, operates at liquid helium temperatures. It includes a broadband commercial amplifier mounted in close proximity to the tunnel junction, thus reducing both the thermal noise and input capacitance that limit traditional noise measurements. The full capabilities of the microscope are maintained in the modified system, and a quick transition between different measurement modes is possible.
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Affiliation(s)
- Idan Tamir
- Fachbereich Physik, Freie Universität Berlin, 14195 Berlin, Germany
| | - Verena Caspari
- Fachbereich Physik, Freie Universität Berlin, 14195 Berlin, Germany
| | - Daniela Rolf
- Fachbereich Physik, Freie Universität Berlin, 14195 Berlin, Germany
| | - Christian Lotze
- Fachbereich Physik, Freie Universität Berlin, 14195 Berlin, Germany
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4
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Bastiaans KM, Chatzopoulos D, Ge JF, Cho D, Tromp WO, van Ruitenbeek JM, Fischer MH, de Visser PJ, Thoen DJ, Driessen EFC, Klapwijk TM, Allan MP. Direct evidence for Cooper pairing without a spectral gap in a disordered superconductor above Tc. Science 2021; 374:608-611. [PMID: 34709897 DOI: 10.1126/science.abe3987] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
[Figure: see text].
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Affiliation(s)
- Koen M Bastiaans
- Leiden Institute of Physics, Leiden University, 2333 CA Leiden, Netherlands
| | | | - Jian-Feng Ge
- Leiden Institute of Physics, Leiden University, 2333 CA Leiden, Netherlands
| | - Doohee Cho
- Department of Physics, Yonsei University, Seoul 03722, Republic of Korea
| | - Willem O Tromp
- Leiden Institute of Physics, Leiden University, 2333 CA Leiden, Netherlands
| | | | - Mark H Fischer
- Department of Physics, University of Zurich, 8057 Zurich, Switzerland
| | - Pieter J de Visser
- SRON Netherlands Institute for Space Research, 2333 CA Leiden Netherlands
| | - David J Thoen
- Kavli Institute of Nanoscience, Delft University of Technology, 2628 CJ Delft, Netherlands.,Faculty of Electrical Engineering, Mathematics and Computer Science, Delft University of Technology, 2628 CD Delft, Netherlands
| | - Eduard F C Driessen
- Institut de Radioastronomie Millimétrique (IRAM), Grenoble, 38400 Saint-Martin-d'Hères, France
| | - Teunis M Klapwijk
- Kavli Institute of Nanoscience, Delft University of Technology, 2628 CJ Delft, Netherlands.,Institute of Topological Materials, Julius-Maximilian-Universität Würzburg, 97070 Würzburg, Germany
| | - Milan P Allan
- Leiden Institute of Physics, Leiden University, 2333 CA Leiden, Netherlands
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5
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Lee S, Hashisaka M, Akiho T, Kobayashi K, Muraki K. Cryogenic GaAs high-electron-mobility-transistor amplifier for current noise measurements. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:023910. [PMID: 33648138 DOI: 10.1063/5.0036419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 01/26/2021] [Indexed: 06/12/2023]
Abstract
We show that a cryogenic amplifier composed of a homemade GaAs high-electron-mobility transistor (HEMT) is suitable for current-noise measurements in a mesoscopic device at dilution-refrigerator temperatures. The lower noise characteristics of our homemade HEMT lead to a lower noise floor in the experimental setup and enable more efficient current-noise measurement than is available with a commercial HEMT. We present the dc transport properties of the HEMT and the gain and noise characteristics of the amplifier. With the amplifier employed for current-noise measurements in a quantum point contact, we demonstrate the high resolution of the measurement setup by comparing it with that of the conventional one using a commercial HEMT.
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Affiliation(s)
- Sanghyun Lee
- NTT Basic Research Laboratories, NTT Corporation, 3-1 Morinosato-Wakamiya, Atsugi, Kanagawa 243-0198, Japan
| | - Masayuki Hashisaka
- NTT Basic Research Laboratories, NTT Corporation, 3-1 Morinosato-Wakamiya, Atsugi, Kanagawa 243-0198, Japan
| | - Takafumi Akiho
- NTT Basic Research Laboratories, NTT Corporation, 3-1 Morinosato-Wakamiya, Atsugi, Kanagawa 243-0198, Japan
| | - Kensuke Kobayashi
- Graduate School of Science, Osaka University, 1-1, Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Koji Muraki
- NTT Basic Research Laboratories, NTT Corporation, 3-1 Morinosato-Wakamiya, Atsugi, Kanagawa 243-0198, Japan
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6
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Li QF, Wang Y, Wang F, Hou Y, Lu Q. 100 MHz large bandwidth preamplifier and record-breaking 50 kHz scanning rate quantum point contact mode probe microscopy imaging with atomic resolution. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:013701. [PMID: 33514189 DOI: 10.1063/5.0024802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Accepted: 12/11/2020] [Indexed: 06/12/2023]
Abstract
The high-bandwidth preamplifier is a vital component designed to increase the scanning speed of a high-speed scanning tunneling microscope (STM). However, the bandwidth is limited not only by the characteristic GΩ feedback resistor RF but also by the characteristic unity-gain-stable operational amplifier (UGS-OPA) in the STM preamplifier. Here, we report that paralleling a resistor with the tunneling junction (PRTJ) can break both limitations. Then, the UGS-OPA can be replaced by a higher rate, higher antinoise ability, decompensated OPA. By doing so, a bandwidth of more than 100 MHz was achieved in the STM preamplifier with decompensated OPA657, and a higher bandwidth is possible. High-clarity atomic resolution STM images were obtained under about 10 MHz bandwidth and quantum point contact microscopy mode with a record-breaking line rate of 50 k lines/s and a record-breaking frame rate of 250 frames/s. Both the PRTJ method and the decompensated OPA will pave the way for higher scanning speeds and play a key role in the design of high-performance STMs.
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Affiliation(s)
- Quan Feng Li
- Henan Key Laboratory of Photovoltaic Materials, School of Physics, Henan Normal University, Xinxiang 453007, People's Republic of China
| | - Yang Wang
- Henan Key Laboratory of Photovoltaic Materials, School of Physics, Henan Normal University, Xinxiang 453007, People's Republic of China
| | - Fang Wang
- College of Electronic and Electrical Engineering, Henan Normal University, Xinxiang 453007, Henan, People's Republic of China
| | - Yubin Hou
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, Anhui, People's Republic of China
| | - Qingyou Lu
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, Anhui, People's Republic of China
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7
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Štubian M, Bobek J, Setvin M, Diebold U, Schmid M. Fast low-noise transimpedance amplifier for scanning tunneling microscopy and beyond. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2020; 91:074701. [PMID: 32752833 DOI: 10.1063/5.0011097] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 06/05/2020] [Indexed: 06/11/2023]
Abstract
A transimpedance amplifier has been designed for scanning tunneling microscopy (STM). The amplifier features low noise (limited by the Johnson noise of the 1 GΩ feedback resistor at low input current and low frequencies), sufficient bandwidth for most STM applications (50 kHz at 35 pF input capacitance), a large dynamic range (0.1 pA-50 nA without range switching), and a low input voltage offset. The amplifier is also suited for placing its first stage into the cryostat of a low-temperature STM, minimizing the input capacitance and reducing the Johnson noise of the feedback resistor. The amplifier may also find applications for specimen current imaging and electron-beam-induced current measurements in scanning electron microscopy and as a photodiode amplifier with a large dynamic range. This paper also discusses the sources of noise including the often neglected effect of non-balanced input impedance of operational amplifiers and describes how to accurately measure and adjust the frequency response of low-current transimpedance amplifiers.
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Affiliation(s)
- Martin Štubian
- Institute of Applied Physics, TU Wien, 1040 Vienna, Austria
| | - Juraj Bobek
- Institute of Applied Physics, TU Wien, 1040 Vienna, Austria
| | - Martin Setvin
- Institute of Applied Physics, TU Wien, 1040 Vienna, Austria
| | - Ulrike Diebold
- Institute of Applied Physics, TU Wien, 1040 Vienna, Austria
| | - Michael Schmid
- Institute of Applied Physics, TU Wien, 1040 Vienna, Austria
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8
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Senkpiel J, Klöckner JC, Etzkorn M, Dambach S, Kubala B, Belzig W, Yeyati AL, Cuevas JC, Pauly F, Ankerhold J, Ast CR, Kern K. Dynamical Coulomb Blockade as a Local Probe for Quantum Transport. PHYSICAL REVIEW LETTERS 2020; 124:156803. [PMID: 32357030 DOI: 10.1103/physrevlett.124.156803] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2019] [Accepted: 03/24/2020] [Indexed: 06/11/2023]
Abstract
Quantum fluctuations are imprinted with valuable information about transport processes. Experimental access to this information is possible, but challenging. We introduce the dynamical Coulomb blockade (DCB) as a local probe for fluctuations in a scanning tunneling microscope (STM) and show that it provides information about the conduction channels. In agreement with theoretical predictions, we find that the DCB disappears in a single-channel junction with increasing transmission following the Fano factor, analogous to what happens with shot noise. Furthermore we demonstrate local differences in the DCB expected from changes in the conduction channel configuration. Our experimental results are complemented by ab initio transport calculations that elucidate the microscopic nature of the conduction channels in our atomic-scale contacts. We conclude that probing the DCB by STM provides a technique complementary to shot noise measurements for locally resolving quantum transport characteristics.
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Affiliation(s)
- Jacob Senkpiel
- Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, 70569 Stuttgart, Germany
| | - Jan C Klöckner
- Okinawa Institute of Science and Technology Graduate University, Onna-son, Okinawa 904-0495, Japan
- Fachbereich Physik, Universität Konstanz, 78457 Konstanz, Germany
| | - Markus Etzkorn
- Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, 70569 Stuttgart, Germany
| | - Simon Dambach
- Institut für Komplexe Quantensysteme and IQST, Universität Ulm, Albert-Einstein-Allee 11, 89069 Ulm, Germany
| | - Björn Kubala
- Institut für Komplexe Quantensysteme and IQST, Universität Ulm, Albert-Einstein-Allee 11, 89069 Ulm, Germany
| | - Wolfgang Belzig
- Fachbereich Physik, Universität Konstanz, 78457 Konstanz, Germany
| | - Alfredo Levy Yeyati
- Departamento de Física Teórica de la Materia Condensada, Condensed Matter Physics Center (IFIMAC), and Instituto Nicolás Cabrera, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Juan Carlos Cuevas
- Departamento de Física Teórica de la Materia Condensada, Condensed Matter Physics Center (IFIMAC), and Instituto Nicolás Cabrera, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Fabian Pauly
- Okinawa Institute of Science and Technology Graduate University, Onna-son, Okinawa 904-0495, Japan
- Fachbereich Physik, Universität Konstanz, 78457 Konstanz, Germany
| | - Joachim Ankerhold
- Institut für Komplexe Quantensysteme and IQST, Universität Ulm, Albert-Einstein-Allee 11, 89069 Ulm, Germany
| | - Christian R Ast
- Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, 70569 Stuttgart, Germany
| | - Klaus Kern
- Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, 70569 Stuttgart, Germany
- Institut de Physique, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
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9
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Natterer FD. Waveform-sequencing for scanning tunneling microscopy based pump-probe spectroscopy and pulsed-ESR. MethodsX 2019; 6:1279-1285. [PMID: 31198689 PMCID: PMC6555875 DOI: 10.1016/j.mex.2019.05.026] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Accepted: 05/23/2019] [Indexed: 11/24/2022] Open
Abstract
We present here the straightforward implementation of pump-probe methods into existing scanning tunneling microscopy (STM) systems. Our method uses the waveform-sequencing abilities of a standard arbitrary waveform generator (AWG) and a simple mechanical relay switch that either connects the regular STM control electronics or the AWG to the STM system. Our upgrade further enables pulsed-ESR excitation for advanced STM based spin-resonance experiments. We demonstrate the technical implementation, signal detection using a lock-in amplifier, and cross-correlation measurements of DC/DC and DC/RF pulses highlighting our ˜5 ns time resolution, here limited by the speed of the available electronics. Our setup is highly versatile and can be extended to suit other needs of STM based investigations such as required in diverse mapping schemes or the coherent manipulation of qubits. •Plug and Play Pump-Probe Capability•One setup for Pump-Probe Spectroscopy and Pulsed-ESR•Waveform Memory Saving and Versatile due to Waveform-Sequencing of Arbitrary Waveforms.
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10
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Massee F, Huang YK, Golden MS, Aprili M. Noisy defects in the high-T c superconductor Bi 2Sr 2CaCu 2O 8+x. Nat Commun 2019; 10:544. [PMID: 30710086 PMCID: PMC6358600 DOI: 10.1038/s41467-019-08518-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Accepted: 01/16/2019] [Indexed: 11/18/2022] Open
Abstract
Dopants and impurities are crucial in shaping the ground state of host materials: semiconducting technology is based on their ability to donate or trap electrons, and they can even be used to transform insulators into high temperature superconductors. Due to limited time resolution, most atomic-scale studies of the latter materials focussed on the effect of dopants on the electronic properties averaged over time. Here, by using atomic-scale current-noise measurements in optimally doped Bi2Sr2CaCu2O8+x, we visualize sub-nanometre sized objects where the tunnelling current-noise is enhanced by at least an order of magnitude. We show that these objects are previously undetected oxygen dopants whose ionization and local environment leads to unconventional charge dynamics resulting in correlated tunnelling events. The ionization of these dopants opens up new routes to dynamically control doping at the atomic scale, enabling the direct visualization of local charging on e.g. high-Tc superconductivity. The effects of dopants in high-temperature superconductors on the surrounding electronic structure give insights into their unconventional microscopic behaviour. Here the authors find a new class of defects that they identify as oxygen dopants whose ionization and local environment induce unusual atomic-scale charge dynamics.
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Affiliation(s)
- F Massee
- Laboratoire de Physique des Solides (CNRS UMR 8502), Bâtiment 510, Université Paris-Sud/Université Paris-Saclay, 91405, Orsay, France.
| | - Y K Huang
- Institute of Physics, University of Amsterdam, 1098 XH, Amsterdam, The Netherlands
| | - M S Golden
- Institute of Physics, University of Amsterdam, 1098 XH, Amsterdam, The Netherlands
| | - M Aprili
- Laboratoire de Physique des Solides (CNRS UMR 8502), Bâtiment 510, Université Paris-Sud/Université Paris-Saclay, 91405, Orsay, France
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11
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Battisti I, Verdoes G, van Oosten K, Bastiaans KM, Allan MP. Definition of design guidelines, construction, and performance of an ultra-stable scanning tunneling microscope for spectroscopic imaging. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:123705. [PMID: 30599565 DOI: 10.1063/1.5064442] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Accepted: 11/19/2018] [Indexed: 06/09/2023]
Abstract
Spectroscopic-imaging scanning tunneling microscopy is a powerful technique to study quantum materials, with the ability to provide information about the local electronic structure with subatomic resolution. However, as most spectroscopic measurements are conducted without feedback to the tip, it is extremely sensitive to vibrations coming from the environment. This requires the use of laboratories with low-vibration facilities combined with a very rigid microscope construction. In this article, we report on the design and fabrication of an ultra-stable scanning tunneling microscope (STM) for spectroscopic-imaging measurements that operates in ultra-high vacuum and at low temperatures (4 K). We start from existing designs with sapphire as the main material and improve the stiffness further by performing finite element analysis calculations for the main components of the microscope to guide design choices on the geometry of the parts. With this strategy, we construct a STM head with measured lowest resonant frequencies above f 0 = 13 kHz for the coarse approach mechanism, a value three times higher than what has been previously reported and in good agreement with the calculations. This allows us to achieve an average vibration level of ∼6 fm / H z , without a dedicated low-vibration lab. We demonstrate the microscope's performance with topographic and spectroscopic measurements on the correlated metal Sr2RhO4, showing the quasiparticle interference pattern in real and reciprocal space with high signal-to-noise ratio.
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Affiliation(s)
- Irene Battisti
- Leiden Institute of Physics, Leiden University, 2333 CA Leiden, The Netherlands
| | - Gijsbert Verdoes
- Leiden Institute of Physics, Leiden University, 2333 CA Leiden, The Netherlands
| | - Kees van Oosten
- Leiden Institute of Physics, Leiden University, 2333 CA Leiden, The Netherlands
| | - Koen M Bastiaans
- Leiden Institute of Physics, Leiden University, 2333 CA Leiden, The Netherlands
| | - Milan P Allan
- Leiden Institute of Physics, Leiden University, 2333 CA Leiden, The Netherlands
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