1
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Hofer J, Gross R, Higgins G, Huebl H, Kieler OF, Kleiner R, Koelle D, Schmidt P, Slater JA, Trupke M, Uhl K, Weimann T, Wieczorek W, Aspelmeyer M. High-Q Magnetic Levitation and Control of Superconducting Microspheres at Millikelvin Temperatures. Phys Rev Lett 2023; 131:043603. [PMID: 37566828 DOI: 10.1103/physrevlett.131.043603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Accepted: 06/27/2023] [Indexed: 08/13/2023]
Abstract
We report the levitation of a superconducting lead-tin sphere with 100 μm diameter (corresponding to a mass of 5.6 μg) in a static magnetic trap formed by two coils in an anti-Helmholtz configuration, with adjustable resonance frequencies up to 240 Hz. The center-of-mass motion of the sphere is monitored magnetically using a dc superconducting quantum interference device as well as optically and exhibits quality factors of up to 2.6×10^{7}. We also demonstrate 3D magnetic feedback control of the motion of the sphere. The setup is housed in a dilution refrigerator operating at 15 mK. By implementing a cryogenic vibration isolation system, we can attenuate environmental vibrations at 200 Hz by approximately 7 orders of magnitude. The combination of low temperature, large mass, and high quality factor provides a promising platform for testing quantum physics in previously unexplored regimes with high mass and long coherence times.
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Affiliation(s)
- J Hofer
- Faculty of Physics, Vienna Center for Quantum Science and Technology (VCQ), University of Vienna, A-1090 Vienna, Austria
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, A-1090 Vienna, Austria
| | - R Gross
- Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, D-85748 Garching, Germany
- Physik-Department, Technische Universität München, D-85748 Garching, Germany
- Munich Center for Quantum Science and Technology (MCQST), D-80799 München, Germany
| | - G Higgins
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, A-1090 Vienna, Austria
- Department of Microtechnology and Nanoscience (MC2), Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
| | - H Huebl
- Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, D-85748 Garching, Germany
- Physik-Department, Technische Universität München, D-85748 Garching, Germany
- Munich Center for Quantum Science and Technology (MCQST), D-80799 München, Germany
| | - O F Kieler
- Physikalisch-Technische Bundesanstalt (PTB), D-38116 Braunschweig, Germany
| | - R Kleiner
- Physikalisches Institut, Center for Quantum Science (CQ) and LISA+, University of Tuebingen, D-72076 Tuebingen, Germany
| | - D Koelle
- Physikalisches Institut, Center for Quantum Science (CQ) and LISA+, University of Tuebingen, D-72076 Tuebingen, Germany
| | - P Schmidt
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, A-1090 Vienna, Austria
| | - J A Slater
- Faculty of Physics, Vienna Center for Quantum Science and Technology (VCQ), University of Vienna, A-1090 Vienna, Austria
| | - M Trupke
- Faculty of Physics, Vienna Center for Quantum Science and Technology (VCQ), University of Vienna, A-1090 Vienna, Austria
| | - K Uhl
- Physikalisches Institut, Center for Quantum Science (CQ) and LISA+, University of Tuebingen, D-72076 Tuebingen, Germany
| | - T Weimann
- Physikalisch-Technische Bundesanstalt (PTB), D-38116 Braunschweig, Germany
| | - W Wieczorek
- Faculty of Physics, Vienna Center for Quantum Science and Technology (VCQ), University of Vienna, A-1090 Vienna, Austria
- Department of Microtechnology and Nanoscience (MC2), Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
| | - M Aspelmeyer
- Faculty of Physics, Vienna Center for Quantum Science and Technology (VCQ), University of Vienna, A-1090 Vienna, Austria
- Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, A-1090 Vienna, Austria
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2
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Martínez-Pérez MJ, Müller B, Lin J, Rodriguez LA, Snoeck E, Kleiner R, Sesé J, Koelle D. Magnetic vortex nucleation and annihilation in bi-stable ultra-small ferromagnetic particles. Nanoscale 2020; 12:2587-2595. [PMID: 31939948 DOI: 10.1039/c9nr08557b] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Vortex-mediated magnetization reversal in individual ultra-small (∼100 nm) ferromagnetic particles at low temperatures is studied by nanoSQUID magnetometry. At zero applied bias field, the flux-closure magnetic state (vortex) and the quasi uniform configuration are bi-stable. This stems from the extremely small size of the nanoparticles that lies very close to the limit of single-domain formation. The analysis of the temperature-dependent (from 0.3 to 70 K) hysteresis of the magnetization allows us to infer the nature of the ground state magnetization configuration. The latter corresponds to a vortex state as also confirmed by electron holography experiments. Based on the simultaneous analysis of the vortex nucleation and annihilation data, we estimate the magnitude of the energy barriers separating the quasi single-domain and the vortex state and their field dependence. For this purpose, we use a modified power-law scaling of the energy barriers as a function of the applied bias field. These studies are essential to test the thermal and temporal stability of flux-closure states stabilized in ultra-small ferromagnets.
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Affiliation(s)
- M J Martínez-Pérez
- Instituto de Ciencia de Materiales de Aragón and Departamento de Física de la Materia Condensada, CSIC-Universidad de Zaragoza, 50009 Zaragoza, Spain. and Fundación ARAID, Avda. de Ranillas, 50018 Zaragoza, Spain
| | - B Müller
- Physikalisches Institut - Experimentalphysik II and Center for Quantum Science (CQ) in LISA+, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
| | - J Lin
- Physikalisches Institut - Experimentalphysik II and Center for Quantum Science (CQ) in LISA+, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
| | - L A Rodriguez
- Departamento de Física, Universidad del Valle, A.A. 25360, Cali, Colombia and Center of Excellence on Novel Materials - CENM, Universidad del Valle, A.A. 25360, Cali, Colombia
| | - E Snoeck
- CEMES-CNRS 29, rue Jeanne Marvig, B.P. 94347, F-31055 Toulouse Cedex, France
| | - R Kleiner
- Physikalisches Institut - Experimentalphysik II and Center for Quantum Science (CQ) in LISA+, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
| | - J Sesé
- Instituto de Ciencia de Materiales de Aragón and Departamento de Física de la Materia Condensada, CSIC-Universidad de Zaragoza, 50009 Zaragoza, Spain. and Laboratorio de Microscopías Avanzadas (LMA), Instituto de Nanociencia de Aragón (INA), Universidad de Zaragoza, 50018 Zaragoza, Spain
| | - D Koelle
- Physikalisches Institut - Experimentalphysik II and Center for Quantum Science (CQ) in LISA+, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
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3
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Martínez-Pérez MJ, Pablo-Navarro J, Müller B, Kleiner R, Magén C, Koelle D, de Teresa JM, Sesé J. NanoSQUID Magnetometry on Individual As-grown and Annealed Co Nanowires at Variable Temperature. Nano Lett 2018; 18:7674-7682. [PMID: 30458106 DOI: 10.1021/acs.nanolett.8b03329] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Performing magnetization studies on individual nanoparticles is a highly demanding task, especially when measurements need to be carried out under large sweeping magnetic fields or variable temperature. Yet, characterization under varying ambient conditions is paramount in order to fully understand the magnetic behavior of these objects, e.g., the formation of nonuniform states or the mechanisms leading to magnetization reversal and thermal stability. This, in turn, is necessary for the integration of magnetic nanoparticles and nanowires into useful devices, e.g., spin-valves, racetrack memories, or magnetic tip probes. Here, we show that nanosuperconducting quantum interference devices based on high critical temperature superconductors are particularly well suited for this task. We have successfully characterized a number of individual Co nanowires grown through focused electron beam induced deposition and subsequently annealed at different temperatures. Magnetization measurements performed under sweeping magnetic fields (up to ∼100 mT) and variable temperature (1.4-80 K) underscore the intrinsic structural and chemical differences between these nanowires. These point to significant changes in the crystalline structure and the resulting effective magnetic anisotropy of the nanowires, and to the nucleation and subsequent vanishing of antiferromagnetic species within the nanowires annealed at different temperatures.
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Affiliation(s)
- M J Martínez-Pérez
- Instituto de Ciencia de Materiales de Aragón and Departamento de Física de la Materia Condensada , CSIC-Universidad de Zaragoza , 50009 Zaragoza , Spain
- Fundación ARAID , 50018 Zaragoza , Spain
| | - J Pablo-Navarro
- Laboratorio de Microscopías Avanzadas (LMA), Instituto de Nanociencia de Aragón (INA) , Universidad de Zaragoza , 50018 Zaragoza , Spain
| | - B Müller
- Physikalisches Institut, Experimentalphysik II and Center for Quantum Science (CQ) in LISA+ , Universität Tübingen , 72076 Tübingen , Germany
| | - R Kleiner
- Physikalisches Institut, Experimentalphysik II and Center for Quantum Science (CQ) in LISA+ , Universität Tübingen , 72076 Tübingen , Germany
| | - C Magén
- Instituto de Ciencia de Materiales de Aragón and Departamento de Física de la Materia Condensada , CSIC-Universidad de Zaragoza , 50009 Zaragoza , Spain
- Laboratorio de Microscopías Avanzadas (LMA), Instituto de Nanociencia de Aragón (INA) , Universidad de Zaragoza , 50018 Zaragoza , Spain
| | - D Koelle
- Physikalisches Institut, Experimentalphysik II and Center for Quantum Science (CQ) in LISA+ , Universität Tübingen , 72076 Tübingen , Germany
| | - J M de Teresa
- Instituto de Ciencia de Materiales de Aragón and Departamento de Física de la Materia Condensada , CSIC-Universidad de Zaragoza , 50009 Zaragoza , Spain
- Laboratorio de Microscopías Avanzadas (LMA), Instituto de Nanociencia de Aragón (INA) , Universidad de Zaragoza , 50018 Zaragoza , Spain
| | - J Sesé
- Instituto de Ciencia de Materiales de Aragón and Departamento de Física de la Materia Condensada , CSIC-Universidad de Zaragoza , 50009 Zaragoza , Spain
- Laboratorio de Microscopías Avanzadas (LMA), Instituto de Nanociencia de Aragón (INA) , Universidad de Zaragoza , 50018 Zaragoza , Spain
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4
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Koshelets V, Kinev N, Ermakov A, Rudau F, Wieland R, Koelle D, Kleiner R, Wang H. Spectral measurements of THz radiation emitted from intrinsic Josephson junction stacks. EPJ Web Conf 2018. [DOI: 10.1051/epjconf/201819505013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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5
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Hattermann H, Bothner D, Ley LY, Ferdinand B, Wiedmaier D, Sárkány L, Kleiner R, Koelle D, Fortágh J. Coupling ultracold atoms to a superconducting coplanar waveguide resonator. Nat Commun 2017; 8:2254. [PMID: 29269855 PMCID: PMC5740063 DOI: 10.1038/s41467-017-02439-7] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Accepted: 11/26/2017] [Indexed: 11/08/2022] Open
Abstract
Ensembles of trapped atoms interacting with on-chip microwave resonators are considered as promising systems for the realization of quantum memories, novel quantum gates, and interfaces between the microwave and optical regime. Here, we demonstrate coupling of magnetically trapped ultracold Rb ground-state atoms to a coherently driven superconducting coplanar resonator on an integrated atom chip. When the cavity is driven off-resonance from the atomic transition, the microwave field strength in the cavity can be measured through observation of the AC shift of the atomic hyperfine transition frequency. When driving the cavity in resonance with the atoms, we observe Rabi oscillations between hyperfine states, demonstrating coherent control of the atomic states through the cavity field. These observations enable the preparation of coherent atomic superposition states, which are required for the implementation of an atomic quantum memory.
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Affiliation(s)
- H Hattermann
- CQ Center for Quantum Science in LISA+, Physikalisches Institut, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 14, D-72076, Tübingen, Germany.
| | - D Bothner
- CQ Center for Quantum Science in LISA+, Physikalisches Institut, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 14, D-72076, Tübingen, Germany
- Kavli Institute of Nanoscience, Delft University of Technology, PO Box 5046, 2600, GA, Delft, The Netherlands
| | - L Y Ley
- CQ Center for Quantum Science in LISA+, Physikalisches Institut, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 14, D-72076, Tübingen, Germany
| | - B Ferdinand
- CQ Center for Quantum Science in LISA+, Physikalisches Institut, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 14, D-72076, Tübingen, Germany
| | - D Wiedmaier
- CQ Center for Quantum Science in LISA+, Physikalisches Institut, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 14, D-72076, Tübingen, Germany
| | - L Sárkány
- CQ Center for Quantum Science in LISA+, Physikalisches Institut, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 14, D-72076, Tübingen, Germany
| | - R Kleiner
- CQ Center for Quantum Science in LISA+, Physikalisches Institut, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 14, D-72076, Tübingen, Germany
| | - D Koelle
- CQ Center for Quantum Science in LISA+, Physikalisches Institut, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 14, D-72076, Tübingen, Germany
| | - J Fortágh
- CQ Center for Quantum Science in LISA+, Physikalisches Institut, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 14, D-72076, Tübingen, Germany
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6
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Lange M, Guénon S, Lever F, Kleiner R, Koelle D. A high-resolution combined scanning laser and widefield polarizing microscope for imaging at temperatures from 4 K to 300 K. Rev Sci Instrum 2017; 88:123705. [PMID: 29289195 DOI: 10.1063/1.5009529] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Polarized light microscopy, as a contrast-enhancing technique for optically anisotropic materials, is a method well suited for the investigation of a wide variety of effects in solid-state physics, as, for example, birefringence in crystals or the magneto-optical Kerr effect (MOKE). We present a microscopy setup that combines a widefield microscope and a confocal scanning laser microscope with polarization-sensitive detectors. By using a high numerical aperture objective, a spatial resolution of about 240 nm at a wavelength of 405 nm is achieved. The sample is mounted on a 4He continuous flow cryostat providing a temperature range between 4 K and 300 K, and electromagnets are used to apply magnetic fields of up to 800 mT with variable in-plane orientation and 20 mT with out-of-plane orientation. Typical applications of the polarizing microscope are the imaging of the in-plane and out-of-plane magnetization via the longitudinal and polar MOKE, imaging of magnetic flux structures in superconductors covered with a magneto-optical indicator film via the Faraday effect, or imaging of structural features, such as twin-walls in tetragonal SrTiO3. The scanning laser microscope furthermore offers the possibility to gain local information on electric transport properties of a sample by detecting the beam-induced voltage change across a current-biased sample. This combination of magnetic, structural, and electric imaging capabilities makes the microscope a viable tool for research in the fields of oxide electronics, spintronics, magnetism, and superconductivity.
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Affiliation(s)
- M Lange
- Physikalisches Institut-Experimentalphysik II and Center for Quantum Science (CQ) in LISA, Universität Tübingen, D-72076 Tübingen, Germany
| | - S Guénon
- Physikalisches Institut-Experimentalphysik II and Center for Quantum Science (CQ) in LISA, Universität Tübingen, D-72076 Tübingen, Germany
| | - F Lever
- Physikalisches Institut-Experimentalphysik II and Center for Quantum Science (CQ) in LISA, Universität Tübingen, D-72076 Tübingen, Germany
| | - R Kleiner
- Physikalisches Institut-Experimentalphysik II and Center for Quantum Science (CQ) in LISA, Universität Tübingen, D-72076 Tübingen, Germany
| | - D Koelle
- Physikalisches Institut-Experimentalphysik II and Center for Quantum Science (CQ) in LISA, Universität Tübingen, D-72076 Tübingen, Germany
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7
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Buckenmaier K, Rudolph M, Back C, Misztal T, Bommerich U, Fehling P, Koelle D, Kleiner R, Mayer HA, Scheffler K, Bernarding J, Plaumann M. SQUID-based detection of ultra-low-field multinuclear NMR of substances hyperpolarized using signal amplification by reversible exchange. Sci Rep 2017; 7:13431. [PMID: 29044168 PMCID: PMC5647402 DOI: 10.1038/s41598-017-13757-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 09/26/2017] [Indexed: 11/15/2022] Open
Abstract
Ultra-low-field (ULF) nuclear magnetic resonance (NMR) is a promising spectroscopy method allowing for, e.g., the simultaneous detection of multiple nuclei. To overcome the low signal-to-noise ratio that usually hampers a wider application, we present here an alternative approach to ULF NMR, which makes use of the hyperpolarizing technique signal amplification by reversible exchange (SABRE). In contrast to standard parahydrogen hyperpolarization, SABRE can continuously hyperpolarize 1 H as well as other MR-active nuclei. For simultaneous measurements of 1 H and 19 F under SABRE conditions a superconducting quantum interference device (SQUID)-based NMR detection unit was adapted. We successfully hyperpolarized fluorinated pyridine derivatives with an up to 2000-fold signal enhancement in 19 F. The detected signals may be explained by two alternative reaction mechanisms. SABRE combined with simultaneous SQUID-based broadband multinuclear detection may enable the quantitative analysis of multinuclear processes.
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Affiliation(s)
- K Buckenmaier
- High-Field Magnetic Resonance Center, Max Planck Institute for Biological Cybernetics, Spemannstr. 41, 72076, Tübingen, Germany.
| | - M Rudolph
- High-Field Magnetic Resonance Center, Max Planck Institute for Biological Cybernetics, Spemannstr. 41, 72076, Tübingen, Germany.,Physikalisches Institut and Center for Quantum Science (CQ) in LISA+, University of Tübingen, Tübingen, Germany
| | - C Back
- Physikalisches Institut and Center for Quantum Science (CQ) in LISA+, University of Tübingen, Tübingen, Germany
| | - T Misztal
- Institute of Inorganic Chemistry, University of Tübingen, Tübingen, Germany
| | - U Bommerich
- Department for Biometrics and Medical Informatics, Otto-von-Guericke University, Magdeburg, Germany
| | - P Fehling
- High-Field Magnetic Resonance Center, Max Planck Institute for Biological Cybernetics, Spemannstr. 41, 72076, Tübingen, Germany
| | - D Koelle
- Physikalisches Institut and Center for Quantum Science (CQ) in LISA+, University of Tübingen, Tübingen, Germany
| | - R Kleiner
- Physikalisches Institut and Center for Quantum Science (CQ) in LISA+, University of Tübingen, Tübingen, Germany
| | - H A Mayer
- Institute of Inorganic Chemistry, University of Tübingen, Tübingen, Germany
| | - K Scheffler
- High-Field Magnetic Resonance Center, Max Planck Institute for Biological Cybernetics, Spemannstr. 41, 72076, Tübingen, Germany
| | - J Bernarding
- Department for Biometrics and Medical Informatics, Otto-von-Guericke University, Magdeburg, Germany
| | - M Plaumann
- Department for Biometrics and Medical Informatics, Otto-von-Guericke University, Magdeburg, Germany
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8
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Nanda G, Aguilera-Servin JL, Rakyta P, Kormányos A, Kleiner R, Koelle D, Watanabe K, Taniguchi T, Vandersypen LMK, Goswami S. Current-Phase Relation of Ballistic Graphene Josephson Junctions. Nano Lett 2017; 17:3396-3401. [PMID: 28474892 PMCID: PMC5474691 DOI: 10.1021/acs.nanolett.7b00097] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Revised: 05/03/2017] [Indexed: 05/22/2023]
Abstract
The current-phase relation (CPR) of a Josephson junction (JJ) determines how the supercurrent evolves with the superconducting phase difference across the junction. Knowledge of the CPR is essential in order to understand the response of a JJ to various external parameters. Despite the rising interest in ultraclean encapsulated graphene JJs, the CPR of such junctions remains unknown. Here, we use a fully gate-tunable graphene superconducting quantum intereference device (SQUID) to determine the CPR of ballistic graphene JJs. Each of the two JJs in the SQUID is made with graphene encapsulated in hexagonal boron nitride. By independently controlling the critical current of the JJs, we can operate the SQUID either in a symmetric or asymmetric configuration. The highly asymmetric SQUID allows us to phase-bias one of the JJs and thereby directly obtain its CPR. The CPR is found to be skewed, deviating significantly from a sinusoidal form. The skewness can be tuned with the gate voltage and oscillates in antiphase with Fabry-Pérot resistance oscillations of the ballistic graphene cavity. We compare our experiments with tight-binding calculations that include realistic graphene-superconductor interfaces and find a good qualitative agreement.
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Affiliation(s)
- G. Nanda
- Kavli
Institute of Nanoscience, Delft University
of Technology, 2600 GA Delft, The Netherlands
| | - J. L. Aguilera-Servin
- Kavli
Institute of Nanoscience, Delft University
of Technology, 2600 GA Delft, The Netherlands
- Institute
of Science and Technology Austria, Am Campus 1, A-3400 Klosterneuburg, Austria
| | - P. Rakyta
- Department
of Physics of Complex Systems, Eötvös
University, Pázmány Péter Sétány 1/A, H-1117 Budapest, Hungary
| | - A. Kormányos
- Department
of Physics, University of Konstanz, D-78464 Konstanz, Germany
| | - R. Kleiner
- Physikalisches
Institut and Center for Quantum Science (CQ) in LISA+, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
| | - D. Koelle
- Physikalisches
Institut and Center for Quantum Science (CQ) in LISA+, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
| | - K. Watanabe
- National
Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - T. Taniguchi
- National
Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - L. M. K. Vandersypen
- Kavli
Institute of Nanoscience, Delft University
of Technology, 2600 GA Delft, The Netherlands
- QuTech, Delft University of
Technology, 2600 GA Delft, The Netherlands
| | - S. Goswami
- Kavli
Institute of Nanoscience, Delft University
of Technology, 2600 GA Delft, The Netherlands
- QuTech, Delft University of
Technology, 2600 GA Delft, The Netherlands
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9
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Goldobin E, Menditto R, Koelle D, Kleiner R. Model I-V curves and figures of merit of underdamped deterministic Josephson ratchets. Phys Rev E 2016; 94:032203. [PMID: 27739827 DOI: 10.1103/physreve.94.032203] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Indexed: 11/07/2022]
Abstract
We propose simple models for the current-voltage characteristics of typical Josephson ratchets. We consider the case of a ratchet working against a constant applied counter force and derive analytical expressions for the key characteristics of such a ratchet: rectification curve, stopping force, input and output powers, and rectification efficiency. Optimization of the ratchet performance is discussed.
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Affiliation(s)
- E Goldobin
- Physikalisches Institut and Center for Quantum Science in LISA+, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
| | - R Menditto
- Physikalisches Institut and Center for Quantum Science in LISA+, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
| | - D Koelle
- Physikalisches Institut and Center for Quantum Science in LISA+, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
| | - R Kleiner
- Physikalisches Institut and Center for Quantum Science in LISA+, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
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10
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Menditto R, Sickinger H, Weides M, Kohlstedt H, Koelle D, Kleiner R, Goldobin E. Tunable φ Josephson junction ratchet. Phys Rev E 2016; 94:042202. [PMID: 27841459 DOI: 10.1103/physreve.94.042202] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Indexed: 06/06/2023]
Abstract
We demonstrate experimentally the operation of a deterministic Josephson ratchet with tunable asymmetry. The ratchet is based on a φ Josephson junction with a ferromagnetic barrier operating in the underdamped regime. The system is probed also under the action of an additional dc current, which acts as a counterforce trying to stop the ratchet. Under these conditions the ratchet works against the counterforce, thus producing a nonzero output power. Finally, we estimate the efficiency of the φ Josephson junction ratchet.
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Affiliation(s)
- R Menditto
- Physikalisches Institut and Center for Quantum Science in LISA+, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
| | - H Sickinger
- Physikalisches Institut and Center for Quantum Science in LISA+, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
| | - M Weides
- Physikalisches Institut, Karlsruher Institut für Technologie, D-76128 Karlsruhe, Germany
| | - H Kohlstedt
- Nanoelektronik, Technische Fakultät, Christian-Albrechts-Universität zu Kiel, D-24143 Kiel, Germany
| | - D Koelle
- Physikalisches Institut and Center for Quantum Science in LISA+, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
| | - R Kleiner
- Physikalisches Institut and Center for Quantum Science in LISA+, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
| | - E Goldobin
- Physikalisches Institut and Center for Quantum Science in LISA+, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
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11
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Thiel L, Rohner D, Ganzhorn M, Appel P, Neu E, Müller B, Kleiner R, Koelle D, Maletinsky P. Quantitative nanoscale vortex imaging using a cryogenic quantum magnetometer. Nat Nanotechnol 2016; 11:677-81. [PMID: 27136133 DOI: 10.1038/nnano.2016.63] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2015] [Accepted: 03/16/2016] [Indexed: 05/05/2023]
Abstract
Microscopic studies of superconductors and their vortices play a pivotal role in understanding the mechanisms underlying superconductivity. Local measurements of penetration depths or magnetic stray fields enable access to fundamental aspects such as nanoscale variations in superfluid densities or the order parameter symmetry of superconductors. However, experimental tools that offer quantitative, nanoscale magnetometry and operate over large ranges of temperature and magnetic fields are still lacking. Here, we demonstrate the first operation of a cryogenic scanning quantum sensor in the form of a single nitrogen-vacancy electronic spin in diamond, which is capable of overcoming these existing limitations. To demonstrate the power of our approach, we perform quantitative, nanoscale magnetic imaging of Pearl vortices in the cuprate superconductor YBa2Cu3O7-δ. With a sensor-to-sample distance of ∼10 nm, we observe striking deviations from the prevalent monopole approximation in our vortex stray-field images, and find excellent quantitative agreement with Pearl's analytic model. Our experiments provide a non-invasive and unambiguous determination of the system's local penetration depth and are readily extended to higher temperatures and magnetic fields. These results demonstrate the potential of quantitative quantum sensors in benchmarking microscopic models of complex electronic systems and open the door for further exploration of strongly correlated electron physics using scanning nitrogen-vacancy magnetometry.
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Affiliation(s)
- L Thiel
- Department of Physics, University of Basel, Klingelbergstrasse 82, Basel CH-4056, Switzerland
| | - D Rohner
- Department of Physics, University of Basel, Klingelbergstrasse 82, Basel CH-4056, Switzerland
| | - M Ganzhorn
- Department of Physics, University of Basel, Klingelbergstrasse 82, Basel CH-4056, Switzerland
| | - P Appel
- Department of Physics, University of Basel, Klingelbergstrasse 82, Basel CH-4056, Switzerland
| | - E Neu
- Department of Physics, University of Basel, Klingelbergstrasse 82, Basel CH-4056, Switzerland
| | - B Müller
- Physikalisches Institut and Center for Quantum Science (CQ) in LISA+, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
| | - R Kleiner
- Physikalisches Institut and Center for Quantum Science (CQ) in LISA+, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
| | - D Koelle
- Physikalisches Institut and Center for Quantum Science (CQ) in LISA+, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
| | - P Maletinsky
- Department of Physics, University of Basel, Klingelbergstrasse 82, Basel CH-4056, Switzerland
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12
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Ma HJH, Scharinger S, Zeng SW, Kohlberger D, Lange M, Stöhr A, Wang XR, Venkatesan T, Kleiner R, Scott JF, Coey JMD, Koelle D. Local Electrical Imaging of Tetragonal Domains and Field-Induced Ferroelectric Twin Walls in Conducting SrTiO_{3}. Phys Rev Lett 2016; 116:257601. [PMID: 27391752 DOI: 10.1103/physrevlett.116.257601] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Indexed: 06/06/2023]
Abstract
We demonstrate electrical mapping of tetragonal domains and electric field-induced twin walls in SrTiO_{3} as a function of temperature and gate bias utilizing the conducting LaAlO_{3}/SrTiO_{3} interface and low-temperature scanning electron microscopy. Conducting twin walls appear below 105 K, and new twin patterns are observed after thermal cycling through the transition or on electric field gating. The nature of the twin walls is confirmed by calculating their intersection angles for different substrate orientations. Numerous walls formed when a large side- or back-gate voltage is applied are identified as field-induced ferroelectric twin walls in the paraelectric tetragonal matrix. The walls persist after switching off the electric field and on thermal cycling below 105 K. These observations point to a new type of ferroelectric functionality in SrTiO_{3}, which could be exploited together with magnetism and superconductivity in a multifunctional context.
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Affiliation(s)
- H J Harsan Ma
- NUSNNI-Nanocore, National University of Singapore, 117411 Singapore, Singapore
- Department of Physics, National University of Singapore, 117542 Singapore, Singapore
| | - S Scharinger
- Physikalisches Institut and Center for Quantum Science (CQ) in LISA+, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
| | - S W Zeng
- NUSNNI-Nanocore, National University of Singapore, 117411 Singapore, Singapore
- Department of Physics, National University of Singapore, 117542 Singapore, Singapore
| | - D Kohlberger
- Physikalisches Institut and Center for Quantum Science (CQ) in LISA+, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
| | - M Lange
- Physikalisches Institut and Center for Quantum Science (CQ) in LISA+, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
| | - A Stöhr
- Physikalisches Institut and Center for Quantum Science (CQ) in LISA+, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
| | - X Renshaw Wang
- NUSNNI-Nanocore, National University of Singapore, 117411 Singapore, Singapore
- Department of Physics, National University of Singapore, 117542 Singapore, Singapore
| | - T Venkatesan
- NUSNNI-Nanocore, National University of Singapore, 117411 Singapore, Singapore
- Department of Physics, National University of Singapore, 117542 Singapore, Singapore
- Department of Electrical and Computer Engineering, National University of Singapore, 117576 Singapore, Singapore
| | - R Kleiner
- Physikalisches Institut and Center for Quantum Science (CQ) in LISA+, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
| | - J F Scott
- School of Chemistry and School of Physics, St. Andrews University, St. Andrews KY16 9ST, United Kingdom
| | - J M D Coey
- NUSNNI-Nanocore, National University of Singapore, 117411 Singapore, Singapore
- Department of Pure and Applied Physics, Trinity College, Dublin 2, Ireland
| | - D Koelle
- Physikalisches Institut and Center for Quantum Science (CQ) in LISA+, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
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13
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Weiss P, Knufinke M, Bernon S, Bothner D, Sárkány L, Zimmermann C, Kleiner R, Koelle D, Fortágh J, Hattermann H. Sensitivity of ultracold atoms to quantized flux in a superconducting ring. Phys Rev Lett 2015; 114:113003. [PMID: 25839266 DOI: 10.1103/physrevlett.114.113003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Indexed: 06/04/2023]
Abstract
We report on the magnetic trapping of an ultracold ensemble of (87)Rb atoms close to a superconducting ring prepared in different states of quantized magnetic flux. The niobium ring of 10 μm radius is prepared in a flux state n Φ(0), where Φ(0)=h/2e is the flux quantum and n varying between ±6. An atomic cloud of 250 nK temperature is positioned with a harmonic magnetic trapping potential at ∼18 μm distance below the ring. The inhomogeneous magnetic field of the supercurrent in the ring contributes to the magnetic trapping potential of the cloud. The induced deformation of the magnetic trap impacts the shape of the cloud, the number of trapped atoms, as well as the center-of-mass oscillation frequency of Bose-Einstein condensates. When the field applied during cooldown of the chip is varied, the change of these properties shows discrete steps that quantitatively match flux quantization.
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Affiliation(s)
- P Weiss
- CQ Center for Collective Quantum Phenomena and their Applications in LISA+, Physikalisches Institut, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
| | - M Knufinke
- CQ Center for Collective Quantum Phenomena and their Applications in LISA+, Physikalisches Institut, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
| | - S Bernon
- CQ Center for Collective Quantum Phenomena and their Applications in LISA+, Physikalisches Institut, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
| | - D Bothner
- CQ Center for Collective Quantum Phenomena and their Applications in LISA+, Physikalisches Institut, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
| | - L Sárkány
- CQ Center for Collective Quantum Phenomena and their Applications in LISA+, Physikalisches Institut, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
| | - C Zimmermann
- CQ Center for Collective Quantum Phenomena and their Applications in LISA+, Physikalisches Institut, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
| | - R Kleiner
- CQ Center for Collective Quantum Phenomena and their Applications in LISA+, Physikalisches Institut, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
| | - D Koelle
- CQ Center for Collective Quantum Phenomena and their Applications in LISA+, Physikalisches Institut, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
| | - J Fortágh
- CQ Center for Collective Quantum Phenomena and their Applications in LISA+, Physikalisches Institut, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
| | - H Hattermann
- CQ Center for Collective Quantum Phenomena and their Applications in LISA+, Physikalisches Institut, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
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14
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Thiessen A, Beyreuther E, Werner R, Kleiner R, Koelle D, Eng LM. Conductivity and magnetoresistance of La0.7Ce0.3MnO(3-δ) thin films under photoexcitation. J Phys Condens Matter 2015; 27:025503. [PMID: 25531984 DOI: 10.1088/0953-8984/27/2/025503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
La0.7Ce0.3MnO3 thin films of different thicknesses, degrees of CeO2-phase segregation and oxygen deficiency, grown on SrTiO3 single crystal substrates, were comparatively investigated with respect to both their spectral and temperature-dependent photoconductivity (PC) and their magnetoresistance (MR) behaviour under photoexcitation. While as-grown films were insensitive to optical excitation, oxygen reduction appeared to be an effective way to decrease the film resistance, but the film thickness was found to play a minor role. However, from the evaluation of the spectral behaviour of the PC and the comparison of the MR of the LCeMO/substrate-samples with a bare substrate under illumination we find that the photoconductivity data reflects not only contributions from (i) photogenerated charge carriers in the film and (ii) carriers injected from the photoconductive substrate (as concluded from earlier works), but also (iii) a decisive parallel photoconduction in the SrTiO3 substrate. Furthermore--also by analyzing the MR characteristics--the unexpected occurence of a strong electroresistive effect in the sample with the highest degree of CeO2 segregation and oxygen deficiency could be attributed to the electroresistance of the SrTiO3 substrate as well. The results suggest a critical reconsideration and possibly a reinterpretation of several previous photoconductivity and electroresistance investigations of manganite thin films on SrTiO3.
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Affiliation(s)
- A Thiessen
- Institut für Angewandte Photophysik, Technische Universität Dresden, D-01062 Dresden, Germany
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15
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Thiessen A, Beyreuther E, Grafström S, Dörr K, Werner R, Kleiner R, Koelle D, Eng LM. The Mn(2+)/Mn(3+) state of La0.7Ce0.3MnO3 by oxygen reduction and photodoping. J Phys Condens Matter 2014; 26:045502. [PMID: 24389924 DOI: 10.1088/0953-8984/26/4/045502] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Films of cerium-doped LaMnO3, which has been intensively discussed as an electron-doped counterpart to hole-doped mixed-valence lanthanum manganites during the past decade, were analyzed by x-ray photoemission spectroscopy with respect to their manganese valence under photoexcitation. The comparative analysis of the Mn 3s exchange splitting of La0.7Ce0.3MnO3 (LCeMO) films in the dark and under illumination clearly shows that both oxygen reduction and illumination are able to decrease the Mn valence towards a mixed 2+/3+ state, independently of the film thickness and the degree of CeO2 segregation. Charge-injection from the photoconductive SrTiO3 substrate into the Mn eg band with carrier lifetimes in the range of tens of seconds and intrinsic generation of electron-hole pairs within the films are discussed as two possible sources of the Mn valence shift and the subsequent electron doping.
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Affiliation(s)
- A Thiessen
- Institut für Angewandte Photophysik, Technische Universität Dresden, D-01062 Dresden, Germany
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16
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Buchter A, Nagel J, Rüffer D, Xue F, Weber DP, Kieler OF, Weimann T, Kohlmann J, Zorin AB, Russo-Averchi E, Huber R, Berberich P, Fontcuberta i Morral A, Kemmler M, Kleiner R, Koelle D, Grundler D, Poggio M. Reversal mechanism of an individual Ni nanotube simultaneously studied by torque and SQUID magnetometry. Phys Rev Lett 2013; 111:067202. [PMID: 23971606 DOI: 10.1103/physrevlett.111.067202] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Revised: 07/14/2013] [Indexed: 05/12/2023]
Abstract
Using an optimally coupled nanometer-scale SQUID, we measure the magnetic flux originating from an individual ferromagnetic Ni nanotube attached to a Si cantilever. At the same time, we detect the nanotube's volume magnetization using torque magnetometry. We observe both the predicted reversible and irreversible reversal processes. A detailed comparison with micromagnetic simulations suggests that vortexlike states are formed in different segments of the individual nanotube. Such stray-field free states are interesting for memory applications and noninvasive sensing.
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Affiliation(s)
- A Buchter
- Department of Physics, University of Basel, 4056 Basel, Switzerland
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17
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Goldobin E, Kleiner R, Koelle D, Mints RG. Phase retrapping in a pointlike φ Josephson junction: the butterfly effect. Phys Rev Lett 2013; 111:057004. [PMID: 23952434 DOI: 10.1103/physrevlett.111.057004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2013] [Indexed: 06/02/2023]
Abstract
We consider a φ Josephson junction, which has a bistable zero-voltage state with the stationary phases ψ = ±φ. In the nonzero voltage state the phase "moves" viscously along a tilted periodic double-well potential. When the tilting is reduced quasistatically, the phase is retrapped in one of the potential wells. We study the viscous phase dynamics to determine in which well (-φ or +φ) the phase is retrapped for a given damping, when the junction returns from the finite-voltage state back to the zero-voltage state. In the limit of low damping, the φ Josephson junction exhibits a butterfly effect-extreme sensitivity of the destination well on damping. This leads to an impossibility to predict the destination well.
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Affiliation(s)
- E Goldobin
- Physikalisches Institut and Center for Collective Quantum Phenomena in LISA+, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
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18
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Heim DM, Pugach NG, Kupriyanov MY, Goldobin E, Koelle D, Kleiner R. Ferromagnetic planar Josephson junction with transparent interfaces: a φ junction proposal. J Phys Condens Matter 2013; 25:215701. [PMID: 23636963 DOI: 10.1088/0953-8984/25/21/215701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We calculate the current-phase relation of a planar Josephson junction with a ferromagnetic weak link located on top of a thin normal metal film. Following experimental observations we assume transparent superconductor-ferromagnet interfaces. This provides the best interlayer coupling and a low suppression of the superconducting correlations penetrating from the superconducting electrodes into the ferromagnetic layer. We show that this Josephson junction is a promising candidate for experimental φ junction realization.
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Affiliation(s)
- D M Heim
- Institut für Quantenphysik and Center for Integrated Quantum Science and Technology (IQST), Universität Ulm, Ulm, Germany.
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19
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Sickinger H, Lipman A, Weides M, Mints RG, Kohlstedt H, Koelle D, Kleiner R, Goldobin E. Experimental evidence of a φ Josephson junction. Phys Rev Lett 2012; 109:107002. [PMID: 23005318 DOI: 10.1103/physrevlett.109.107002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2012] [Indexed: 06/01/2023]
Abstract
We demonstrate experimentally the existence of Josephson junctions having a doubly degenerate ground state with an average Josephson phase ψ=±φ. The value of φ can be chosen by design in the interval 0<φ<π. The junctions used in our experiments are fabricated as 0-π Josephson junctions of moderate normalized length with asymmetric 0 and π regions. We show that (a) these φ Josephson junctions have two critical currents, corresponding to the escape of the phase ψ from -φ and +φ states, (b) the phase ψ can be set to a particular state by tuning an external magnetic field, or (c) by using a proper bias current sweep sequence. The experimental observations are in agreement with previous theoretical predictions.
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Affiliation(s)
- H Sickinger
- Physikalisches Institut and Center for Collective Quantum Phenomena in LISA, Universität Tübingen, Tübingen, Germany
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20
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Knufinke M, Ilin K, Siegel M, Koelle D, Kleiner R, Goldobin E. Deterministic Josephson vortex ratchet with a load. Phys Rev E Stat Nonlin Soft Matter Phys 2012; 85:011122. [PMID: 22400527 DOI: 10.1103/physreve.85.011122] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2011] [Indexed: 05/31/2023]
Abstract
We investigate experimentally a deterministic underdamped Josephson vortex ratchet-a fluxon particle moving along a Josephson junction in an asymmetric periodic potential. By applying a sinusoidal driving current, one can compel the vortex to move in a certain direction, producing an average dc voltage across the junction. Being in such a rectification regime, we also load the ratchet, i.e., apply an additional dc bias current I(dc) (counterforce) which tilts the potential so that the fluxon climbs uphill due to the ratchet effect. The value of the bias current at which the fluxon stops climbing up defines the strength of the ratchet effect and is determined experimentally. This allows us to estimate the loading capability of the ratchet, the output power, and the efficiency. For the quasistatic regime we present a simple model which delivers straightforward analytic expressions for the above-mentioned figures of merit.
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Affiliation(s)
- M Knufinke
- Physikalisches Institut-Experimentalphysik II and Center for Collective Quantum Phenomena in LISA+, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
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21
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Goldobin E, Koelle D, Kleiner R, Mints RG. Josephson junction with a magnetic-field tunable ground state. Phys Rev Lett 2011; 107:227001. [PMID: 22182037 DOI: 10.1103/physrevlett.107.227001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Indexed: 05/31/2023]
Abstract
We consider an asymmetric 0-π Josephson junction consisting of 0 and π regions of different lengths L(0) and L(π). As predicted earlier this system can be described by an effective sine-Gordon equation for the spatially averaged phase ψ so that the effective current-phase relation of this system includes a negative second harmonic ∝sin(2ψ). If its amplitude is large enough, the ground state of the junction is doubly degenerate ψ=±φ, where φ depends on the amplitudes of the first and second harmonics. We study the behavior of such a junction in an applied magnetic field H and demonstrate that H induces an additional term ∝Hcosψ in the effective current-phase relation. This results in a nontrivial ground state tunable by magnetic field. The dependence of the critical current on H allows for revealing the ground state experimentally.
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Affiliation(s)
- E Goldobin
- Physikalisches Institut and Center for Collective Quantum Phenomena in LISA, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
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22
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Wang HB, Guénon S, Gross B, Yuan J, Jiang ZG, Zhong YY, Grünzweig M, Iishi A, Wu PH, Hatano T, Koelle D, Kleiner R. Coherent terahertz emission of intrinsic Josephson junction stacks in the hot spot regime [corrected]. Phys Rev Lett 2010; 105:057002. [PMID: 20867948 DOI: 10.1103/physrevlett.105.057002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2010] [Indexed: 05/29/2023]
Abstract
We report on THz emission measurements and low temperature scanning laser imaging of Bi2Sr2CaCu2O8 intrinsic Josephson junction stacks. Coherent emission is observed at large dc input power, where a hot spot and a standing wave, formed in the "cold" part of the stack, coexist. By changing bias current and bath temperature, the emission frequency can be varied by more than 40%; the variation matches the Josephson-frequency variation with voltage. The linewidth of radiation is much smaller than expected from a purely cavity-induced synchronization. Thus, an additional mechanism seems to play a role. Some scenarios, related to the presence of the hot spot, are discussed.
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Affiliation(s)
- H B Wang
- National Institute for Materials Science, Tsukuba 3050047, Japan
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23
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Abstract
A three-junction SQUID forms a rocking ratchet for the phase differences across the Josephson junctions. In this Letter we investigate its capability to rectify voltages under stochastic drive currents with a white frequency spectrum up to a cutoff frequency f_{cut}. Experimentally, we accessed the adiabatic regime and find very good agreement with theory. Numerically, we also investigated large values of f_{cut} and find, in agreement with the laws of thermodynamics, that the response disappears, as f_{cut} becomes much larger than the characteristic frequency scales of the system.
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Affiliation(s)
- A Sterck
- Physikalisches Institut and Center for Collective Quantum Phenomena, Universität Tübingen, D-72076 Tübingen, Germany
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24
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Wang HB, Guénon S, Yuan J, Iishi A, Arisawa S, Hatano T, Yamashita T, Koelle D, Kleiner R. Hot spots and waves in Bi2Sr2CaCu2O8 intrinsic Josephson junction stacks: a study by low temperature scanning laser microscopy. Phys Rev Lett 2009; 102:017006. [PMID: 19257232 DOI: 10.1103/physrevlett.102.017006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2008] [Indexed: 05/27/2023]
Abstract
Recently, it has been shown that large stacks of intrinsic Josephson junctions in Bi2Sr2CaCu2O8 emit synchronous THz radiation, the synchronization presumably triggered by a cavity resonance. To investigate this effect we use low temperature scanning laser microscopy to image electric field distributions. We verify the appearance of cavity modes at low bias and in the high input-power regime we find that standing-wave patterns are created through interactions with a hot spot, possibly pointing to a new mode of generating synchronized radiation in intrinsic Josephson junction stacks.
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Affiliation(s)
- H B Wang
- National Institute for Materials Science, Tsukuba 3050047, Japan
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25
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Cano D, Kasch B, Hattermann H, Kleiner R, Zimmermann C, Koelle D, Fortágh J. Meissner effect in superconducting microtraps. Phys Rev Lett 2008; 101:183006. [PMID: 18999830 DOI: 10.1103/physrevlett.101.183006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2008] [Indexed: 05/27/2023]
Abstract
We report on the realization and characterization of a magnetic microtrap for ultracold atoms near a straight superconducting Nb wire with circular cross section. The trapped atoms are used to probe the magnetic field outside the superconducting wire. The Meissner effect shortens the distance between the trap and the wire, reduces the radial magnetic-field gradients, and lowers the trap depth. Measurements of the trap position reveal a complete exclusion of the magnetic field from the superconducting wire for temperatures lower than 6 K. As the temperature is further increased, the magnetic field partially penetrates the superconducting wire; hence the microtrap position is shifted towards the position expected for a normal-conducting wire.
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Affiliation(s)
- D Cano
- Physikalisches Institut, Eberhard-Karls-Universität Tübingen, CQ Center for Collective Quantum Phenomena and their Applications, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
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26
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Wagenknecht M, Koelle D, Kleiner R, Graser S, Schopohl N, Chesca B, Tsukada A, Goennenwein STB, Gross R. Phase diagram of the electron-doped La2-xCexCuO4 cuprate superconductor from Andreev bound states at grain boundary junctions. Phys Rev Lett 2008; 100:227001. [PMID: 18643446 DOI: 10.1103/physrevlett.100.227001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2007] [Indexed: 05/26/2023]
Abstract
We use quasiparticle tunneling across La2-xCexCuO4 grain boundary junctions to probe the superconducting state and its disappearance with increasing temperature and magnetic field. A zero bias conductance peak due to zero energy surface Andreev bound states is a clear signature of the phase coherence of the superconducting state. Hence, such a peak must disappear at or below the upper critical field Bc2(T). For La2-xCexCuO4 this approach sets a lower bound for Bc2(0) approximately 25 T which is substantially higher than reported previously. The method of probing the superconducting state via Andreev bound states should also be applicable to other cuprate superconductors.
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Affiliation(s)
- M Wagenknecht
- Physikalisches Institut-Experimentalphysik II and Center for Collective Quantum Phenomena, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany.
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Nagel J, Speer D, Gaber T, Sterck A, Eichhorn R, Reimann P, Ilin K, Siegel M, Koelle D, Kleiner R. Observation of negative absolute resistance in a Josephson junction. Phys Rev Lett 2008; 100:217001. [PMID: 18518625 DOI: 10.1103/physrevlett.100.217001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2008] [Indexed: 05/26/2023]
Abstract
We experimentally demonstrate the occurrence of negative absolute resistance (NAR) up to about -1 Omega in response to an externally applied dc current for a shunted Nb-Al/AlO_{x}-Nb Josephson junction, exposed to a microwave current at frequencies in the GHz range. The realization (or not) of NAR depends crucially on the amplitude of the applied microwave current. Theoretically, the system is described by means of the resistively and capacitively shunted junction model in terms of a moderately damped, classical Brownian particle dynamics in a one-dimensional potential. We find excellent agreement of the experimental results with numerical simulations of the model.
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Affiliation(s)
- J Nagel
- Physikalisches Institut - Experimentalphysik II, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
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Buckenmaier K, Gaber T, Siegel M, Koelle D, Kleiner R, Goldobin E. Spectroscopy of the fractional vortex eigenfrequency in a long Josephson 0-kappa junction. Phys Rev Lett 2007; 98:117006. [PMID: 17501081 DOI: 10.1103/physrevlett.98.117006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2006] [Indexed: 05/15/2023]
Abstract
Fractional Josephson vortices carry a magnetic flux Phi, which is a fraction of the magnetic flux quantum Phi(0) approximately 2.07 x 10(-15) Wb. Their properties are very different from the properties of the usual integer fluxons. In particular, fractional vortices in 0-kappa Josephson junctions are pinned and have an oscillation eigenfrequency which is expected to be within the Josephson plasma gap. Using microwave spectroscopy, we investigate the dependence of the eigenfrequency of a fractional Josephson vortex on its magnetic flux Phi and on the bias current. The experimental results are in good agreement with the theory.
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Affiliation(s)
- K Buckenmaier
- Physikalisches Institut-Experimentalphysik II, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
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29
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Weides M, Kemmler M, Kohlstedt H, Waser R, Koelle D, Kleiner R, Goldobin E. 0-pi Josephson tunnel junctions with ferromagnetic barrier. Phys Rev Lett 2006; 97:247001. [PMID: 17280309 DOI: 10.1103/physrevlett.97.247001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2006] [Indexed: 05/13/2023]
Abstract
We fabricated high quality Nb/Al2O3/Ni(0.6)Cu(0.4)/Nb superconductor-insulator-ferromagnet-superconductor Josephson tunnel junctions. Using a ferromagnetic layer with a steplike thickness, we obtain a 0-pi junction, with equal lengths and critical currents of 0 and pi parts. The ground state of our 330 microm (1.3lambda(J)) long junction corresponds to a spontaneous vortex of supercurrent pinned at the 0-pi step and carrying approximately 6.7% of the magnetic flux quantum Phi(0). The dependence of the critical current on the applied magnetic field shows a clear minimum in the vicinity of zero field.
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Affiliation(s)
- M Weides
- Center of Nanoelectronic Systems for Information Technology (CNI), Research Centre Jülich, D-52425 Jülich, Germany.
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Kemmler M, Gürlich C, Sterck A, Pöhler H, Neuhaus M, Siegel M, Kleiner R, Koelle D. Commensurability effects in superconducting Nb films with quasiperiodic pinning arrays. Phys Rev Lett 2006; 97:147003. [PMID: 17155286 DOI: 10.1103/physrevlett.97.147003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2006] [Indexed: 05/12/2023]
Abstract
We study experimentally the critical depinning current I(c) versus applied magnetic field B in Nb thin films which contain 2D arrays of circular antidots placed on the nodes of quasiperiodic (QP) fivefold Penrose lattices. Close to the transition temperature T(c) we observe matching of the vortex lattice with the QP pinning array, confirming essential features in the I(c)(B) patterns as predicted by Misko et al. [Phys. Rev. Lett. 95, 177007 (2005)]. We find a significant enhancement in I(c)(B) for QP pinning arrays in comparison to I(c) in samples with randomly distributed antidots or no antidots.
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Affiliation(s)
- M Kemmler
- Physikalisches Institut-Experimentalphysik II, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
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31
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Fritzsche J, Moshchalkov VV, Eitel H, Koelle D, Kleiner R, Szymczak R. Local observation of reverse-domain superconductivity in a superconductor-ferromagnet hybrid. Phys Rev Lett 2006; 96:247003. [PMID: 16907272 DOI: 10.1103/physrevlett.96.247003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2006] [Indexed: 05/11/2023]
Abstract
Nanoscale magnetic and superconducting properties of the superconductor-ferromagnet Nb/PbFe12O19 hybrid were studied as a function of applied magnetic fields. Low-temperature scanning laser microscopy (LTSLM) together with transport measurements were carried out in order to reveal local variations of superconductivity induced by the magnetic field template produced by the ferromagnetic substrate. Room temperature magnetic force microscopy (MFM) was performed and magnetization curves were taken at room and low temperature to investigate the magnetic properties of the hybrid. Comparative analysis of the LTSLM and the MFM images has convincingly demonstrated the presence of the reverse-domain superconductivity.
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Affiliation(s)
- J Fritzsche
- INPAC - Institute for Nanoscale Physics and Chemistry, Nanoscale Superconductivity and Magnetism & Pulsed Fields Group, Katholieke Universiteit Leuven, Celestijnenlaan 200D, B-3001 Leuven, Belgium
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32
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Wagenknecht M, Eitel H, Nachtrab T, Philipp JB, Gross R, Kleiner R, Koelle D. Laser microscopy of tunneling magnetoresistance in manganite grain-boundary junctions. Phys Rev Lett 2006; 96:047203. [PMID: 16486883 DOI: 10.1103/physrevlett.96.047203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2005] [Indexed: 05/06/2023]
Abstract
Using low-temperature scanning laser microscopy we directly image electric transport in a magnetoresistive element, a manganite thin film intersected by a grain boundary (GB). Imaging at variable temperature allows reconstruction and comparison of the local resistance versus temperature for both the manganite film and the GB. Imaging at low temperature also shows that the GB switches between different resistive states due to the formation and growth of magnetic domains along the GB. We observe different types of domain wall growth; in most cases a domain wall nucleates at one edge of the bridge and then proceeds towards the other edge.
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Affiliation(s)
- M Wagenknecht
- Physikalisches Institut-Experimentalphysik II, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
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Abstract
We investigate three-junction SQUIDs which show voltage rectification if biased with an ac current drive with zero mean value. The Josephson phase across the SQUID experiences an effective ratchet potential, and the device acts as an efficient rocking ratchet, as demonstrated experimentally for adiabatic and nonadiabatic drive frequencies. For high-frequency drives the rectified voltage is quantized due to synchronization of the phase dynamics with the external drive. The experimental data are in excellent agreement with numerical simulations including thermal fluctuations.
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Affiliation(s)
- A Sterck
- Physikalisches Institut-Experimentalphysik II, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
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Günther A, Kraft S, Kemmler M, Koelle D, Kleiner R, Zimmermann C, Fortágh J. Diffraction of a Bose-Einstein condensate from a magnetic lattice on a microchip. Phys Rev Lett 2005; 95:170405. [PMID: 16383802 DOI: 10.1103/physrevlett.95.170405] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2005] [Indexed: 05/05/2023]
Abstract
We experimentally study the diffraction of a Bose-Einstein condensate from a magnetic lattice, realized by a set of 372 parallel gold conductors which are microfabricated on a silicon substrate. The conductors generate a periodic potential for the atoms with a lattice constant of 4 microm. After exposing the condensate to the lattice for several milliseconds we observe diffraction up to fifth order by standard time of flight imaging techniques. The experimental data can be quantitatively interpreted with a simple phase imprinting model. The demonstrated diffraction grating offers promising perspectives for the construction of an integrated atom interferometer.
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Affiliation(s)
- A Günther
- Physikalisches Institut der Universität Tübingen, Auf der Morgenstelle 14, 72076 Tübingen, Germany.
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35
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Beck M, Goldobin E, Neuhaus M, Siegel M, Kleiner R, Koelle D. High-efficiency deterministic Josephson vortex ratchet. Phys Rev Lett 2005; 95:090603. [PMID: 16197200 DOI: 10.1103/physrevlett.95.090603] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2005] [Indexed: 05/04/2023]
Abstract
We investigate experimentally a Josephson vortex ratchet--a fluxon in an asymmetric periodic potential driven by a deterministic force with zero time average. The highly asymmetric periodic potential is created in an underdamped annular long Josephson junction by means of a current injector providing an efficiency of the device up to 91%. We measured the ratchet effect for driving forces with different spectral content. For monochromatic high-frequency drive the rectified voltage becomes quantized. At high driving frequencies we also observe chaos, subharmonic dynamics, and voltage reversal due to the inertial mass of a fluxon.
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Affiliation(s)
- M Beck
- Physikalisches Institut-Experimentalphysik II, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
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Nachtrab T, Koelle D, Kleiner R, Bernhard C, Lin CT. Intrinsic Josephson effects in the magnetic superconductor RuSr2GdCu2O8. Phys Rev Lett 2004; 92:117001. [PMID: 15089159 DOI: 10.1103/physrevlett.92.117001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2003] [Indexed: 05/24/2023]
Abstract
We have measured interlayer current transport in small-sized RuSr2GdCu2O8 single crystals. We find a clear intrinsic Josephson effect showing that the material acts as a natural superconductor-insulator-ferromagnet-insulator-superconductor superlattice. Thus far, we detected no unconventional behavior due to the magnetism of the RuO2 layers.
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Affiliation(s)
- T Nachtrab
- Physikalisches Institut-Experimentalphysik II, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
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Goldobin E, Sterck A, Gaber T, Koelle D, Kleiner R. Dynamics of semifluxons in Nb long Josephson 0-pi junctions. Phys Rev Lett 2004; 92:057005. [PMID: 14995336 DOI: 10.1103/physrevlett.92.057005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2003] [Indexed: 05/24/2023]
Abstract
We propose, implement, and test experimentally long Josephson 0-pi junctions fabricated using conventional Nb-AlOx-Nb technology. We show that by using a pair of current injectors one can create an arbitrary discontinuity of the Josephson phase and, in particular, a pi discontinuity, just as in d-wave/s-wave or in d-wave/d-wave junctions, and study fractional Josephson vortices which spontaneously appear. Moreover, using such junctions, we can investigate the dynamics of the fractional vortices-a domain which is not yet available for natural 0-pi junctions due to their inherently high damping. We observe half-integer zero-field steps which appear on the current-voltage characteristics due to the hopping of semifluxons.
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Affiliation(s)
- E Goldobin
- Physikalisches Institut, Experimentalphysik II, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tuebingen, Germany.
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38
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Chesca B, Ehrhardt K, Mössle M, Straub R, Koelle D, Kleiner R, Tsukada A. Magnetic-field dependence of the maximum supercurrent of La2-xCexCuO4-y interferometers: evidence for a predominant dx2-y2 superconducting order parameter. Phys Rev Lett 2003; 90:057004. [PMID: 12633392 DOI: 10.1103/physrevlett.90.057004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2002] [Indexed: 05/24/2023]
Abstract
We performed a phase-sensitive test of the symmetry of the superconducting order parameter of the electron doped cuprate La(2-x)Ce(x)CuO(4-y) using a superconducting quantum interferometer with spatially distributed Josephson junctions. The studies were made on a thin film grown on a SrTiO3 tetracrystal substrate. The superconducting transition temperature was about 29 K which indicates that the sample is close to optimal doping. The magnetic field dependence of the critical current gives strong evidence for a predominant dx(2)(-y(2)) order parameter symmetry of the sample measured. It also gives upper limits for the s-wave component in a mixed order parameter of the type s+idx(2)(-y(2)).
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Affiliation(s)
- B Chesca
- Physikalisches Institut-Experimentalphysik II, Universität Tübingen, auf der Morgenstelle 14, Germany
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Mason JO, Kleiner R. Combined hamartoma of the retina and retinal pigment epithelium associated with epiretinal membrane and macular hole. Retina 2001; 17:160-2. [PMID: 9143046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- J O Mason
- Wills Eye Hospital, Philadelphia, Pennsylvania, USA
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Recchia FM, Baumal CR, Sivalingam A, Kleiner R, Duker JS, Vrabec TR. Endophthalmitis after pediatric strabismus surgery. Arch Ophthalmol 2000; 118:939-44. [PMID: 10900107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
OBJECTIVE To report 6 cases of endophthalmitis after pediatric strabismus surgery. METHODS Retrospective review of initial signs, clinical findings, treatment, culture results, and visual and anatomical outcomes in 6 eyes of 6 children treated at 2 tertiary care institutions between 1983 and 1998. RESULTS Four boys and 2 girls aged 8 months to 6 years (median age, 2 years) developed lethargy and asymmetric eye redness, with or without eyelid swelling or fever, within 4 days of surgery. At diagnosis (median, postoperative day 6) clinical findings included periorbital swelling, redness and leukocoria due to vitritis, and, in some cases, hypopyon. Treatment included pars plana vitrectomy and intravitreal and systemic antibiotics in all cases. Vitreous cultures grew Streptococcus pneumoniae, Haemophilus influenzae, and Staphylococcus aureus. Within 6 months of strabismus surgery, visual acuity was no light perception in all eyes and 3 eyes had been enucleated. The 3 remaining eyes were prephthisical. CONCLUSIONS Endophthalmitis after pediatric strabismus surgery is rare. Children may not recognize or verbalize symptoms. Causative organisms are virulent. Visual and anatomical outcomes are poor. Lethargy, asymmetric eye redness, eyelid swelling, or fever in the postoperative period, even if initial postoperative examination results are normal, should prompt urgent ocular examination. The diagnosis of endophthalmitis may be made when biomicroscopic or indirect ophthalmoscopic examination confirms the presence of vitreous opacification with or without hypopyon. Arch Ophthalmol. 2000;118:939-944
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Affiliation(s)
- F M Recchia
- Wills Eye Hospital, 900 Walnut St, Philadelphia, PA 19107, USA
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Hechtfischer G, Kleiner R, Ustinov A, Müller P. Josephson vortex motion in stacks of intrinsic Josephson junctions in Bi2Sr2CaCu2O8+x. ACTA ACUST UNITED AC 1997. [DOI: 10.1016/s0964-1807(98)00004-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Waldmann O, Lichtschlag G, Talalaevskii A, Kleiner R, Müller P, Steinmeyer F, Gerhäuser W. c-axis ac susceptibility in high-Tc superconductors. Phys Rev B Condens Matter 1996; 54:15478-15482. [PMID: 9985616 DOI: 10.1103/physrevb.54.15478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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43
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Schlenga K, Hechtfischer G, Kleiner R, Walkenhorst W, Müller P, Johnson HL, Veith M, Brodkorb W, Steinbeiss E. Subgap Structures in Intrinsic Josephson Junctions of Tl2Ba2Ca2Cu3O10+ delta and Bi2Sr2CaCu2O8+ delta. Phys Rev Lett 1996; 76:4943-4946. [PMID: 10061419 DOI: 10.1103/physrevlett.76.4943] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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44
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Kleiner R, Katz AS, Sun AG, Summer R, Gajewski DA, Han SH, Woods SI, Dantsker E, Chen B, Char K, Maple MB, Dynes RC, Clarke J. Pair tunneling from c-axis YBa2Cu3O7-x to Pb: Evidence for s-wave component from microwave induced steps. Phys Rev Lett 1996; 76:2161-2164. [PMID: 10060621 DOI: 10.1103/physrevlett.76.2161] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Kleiner R, Müller P, Kohlstedt H, Pedersen NF, Sakai S. Dynamic behavior of Josephson-coupled layered structures. Phys Rev B Condens Matter 1994; 50:3942-3952. [PMID: 9976672 DOI: 10.1103/physrevb.50.3942] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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49
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Kleiner R, Steinmeyer F, Kunkel G, Müller P. Intrinsic Josephson effects in Bi2Sr2CaCu2O8 single crystals. Phys Rev Lett 1992; 68:2394-2397. [PMID: 10045384 DOI: 10.1103/physrevlett.68.2394] [Citation(s) in RCA: 102] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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50
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Regillo CD, Vander JF, Duker JS, Fischer DH, Belmont JB, Kleiner R. Repair of retinitis-related retinal detachments with silicone oil in patients with acquired immunodeficiency syndrome. Am J Ophthalmol 1992; 113:21-7. [PMID: 1309409 DOI: 10.1016/s0002-9394(14)75747-2] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
To provide prompt visual rehabilitation and to reduce the need for repeated operations, we performed vitrectomy with silicone oil tamponade in 16 consecutive eyes with retinal detachments related to cytomegalovirus retinitis and acute retinal necrosis in 13 patients with acquired immunodeficiency syndrome. In all 16 eyes (100%), retinas were reattached with one operation. Preservation of ambulatory vision was achieved in six of eight eyes (75%; mean follow-up, 14.6 weeks). No patient with hand motion visual acuity or worse preoperatively recovered ambulatory vision. Visual acuity recovery was limited by optic nerve disease in five eyes (31%). Silicone oil-related side effects did not adversely affect visual outcome in any eye. Six patients (46%) have since died (mean, 4.4 months postoperatively). These data indicated that successful surgical repair of these detachments can be consistently achieved with this approach. The prognosis for ambulatory vision is strongly related to preoperative visual acuity.
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Affiliation(s)
- C D Regillo
- Retina Service, Wills Eye Hospital, Thomas Jefferson University, Philadelphia, Pennsylvania
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