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Superconducting Bio-Inspired Au-Nanowire-Based Neurons. NANOMATERIALS 2022; 12:nano12101671. [PMID: 35630895 PMCID: PMC9147065 DOI: 10.3390/nano12101671] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 04/27/2022] [Accepted: 05/10/2022] [Indexed: 02/01/2023]
Abstract
High-performance modeling of neurophysiological processes is an urgent task that requires new approaches to information processing. In this context, two- and three-junction superconducting quantum interferometers with Josephson weak links based on gold nanowires are fabricated and investigated experimentally. The studied cells are proposed for the implementation of bio-inspired neurons—high-performance, energy-efficient, and compact elements of neuromorphic processor. The operation modes of an advanced artificial neuron capable of generating the burst firing activation patterns are explored theoretically. A comparison with the Izhikevich mathematical model of biological neurons is carried out.
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Accurate Determination of the Josephson Critical Current by Lock-In Measurements. NANOMATERIALS 2021; 11:nano11082058. [PMID: 34443889 PMCID: PMC8398034 DOI: 10.3390/nano11082058] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 07/30/2021] [Accepted: 08/10/2021] [Indexed: 12/03/2022]
Abstract
Operation of Josephson electronics usually requires determination of the Josephson critical current Ic, which is affected both by fluctuations and measurement noise. Lock-in measurements allow obviation of 1/f noise, and therefore, provide a major advantage in terms of noise and accuracy with respect to conventional dc measurements. In this work we show both theoretically and experimentally that the Ic can be accurately extracted using first and third harmonic lock-in measurements of junction resistance. We derived analytical expressions and verified them experimentally on nano-scale Nb–PtNi–Nb and Nb–CuNi–Nb Josephson junctions.
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3
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Golod T, Hovhannisyan RA, Kapran OM, Dremov VV, Stolyarov VS, Krasnov VM. Reconfigurable Josephson Phase Shifter. NANO LETTERS 2021; 21:5240-5246. [PMID: 34114467 PMCID: PMC8289326 DOI: 10.1021/acs.nanolett.1c01366] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 06/08/2021] [Indexed: 06/01/2023]
Abstract
Phase shifter is one of the key elements of quantum electronics. In order to facilitate operation and avoid decoherence, it has to be reconfigurable, persistent, and nondissipative. In this work, we demonstrate prototypes of such devices in which a Josephson phase shift is generated by coreless superconducting vortices. The smallness of the vortex allows a broad-range tunability by nanoscale manipulation of vortices in a micron-size array of vortex traps. We show that a phase shift in a device containing just a few vortex traps can be reconfigured between a large number of quantized states in a broad [-3π, +3π] range.
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Affiliation(s)
- Taras Golod
- Department
of Physics, Stockholm University, AlbaNova University Center, SE-10691 Stockholm, Sweden
| | - Razmik A. Hovhannisyan
- Department
of Physics, Stockholm University, AlbaNova University Center, SE-10691 Stockholm, Sweden
- Moscow
Institute of Physics and Technology, 141700 Dolgoprudny, Russia
| | - Olena M. Kapran
- Department
of Physics, Stockholm University, AlbaNova University Center, SE-10691 Stockholm, Sweden
| | | | | | - Vladimir M. Krasnov
- Department
of Physics, Stockholm University, AlbaNova University Center, SE-10691 Stockholm, Sweden
- Moscow
Institute of Physics and Technology, 141700 Dolgoprudny, Russia
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4
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Zhu X. Second-Order Topological Superconductors with Mixed Pairing. PHYSICAL REVIEW LETTERS 2019; 122:236401. [PMID: 31298896 DOI: 10.1103/physrevlett.122.236401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Revised: 04/03/2019] [Indexed: 06/10/2023]
Abstract
We show that a two-dimensional semiconductor with Rashba spin-orbit coupling could be driven into the second-order topological superconducting phase when a mixed-pairing state is introduced. The superconducting order we consider involves only even-parity components and meanwhile breaks time-reversal symmetry. As a result, each corner of a square-shaped Rashba semiconductor would host one single Majorana zero mode in the second-order nontrivial phase. Starting from edge physics, we are able to determine the phase boundaries accurately. A simple criterion for the second-order phase is further established, which concerns the relative position between Fermi surfaces and nodal points of the superconducting order parameter. In the end, we propose two setups that may bring this mixed-pairing state into the Rashba semiconductor, followed by a brief discussion on the experimental feasibility of the two platforms.
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Affiliation(s)
- Xiaoyu Zhu
- School of Science, MOE Key Laboratory for Non-equilibrium Synthesis and Modulation of Condensed Matter, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, China
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5
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Ghigo G, Torsello D, Ummarino GA, Gozzelino L, Tanatar MA, Prozorov R, Canfield PC. Disorder-Driven Transition from s_{±} to s_{++} Superconducting Order Parameter in Proton Irradiated Ba(Fe_{1-x}Rh_{x})_{2}As_{2} Single Crystals. PHYSICAL REVIEW LETTERS 2018; 121:107001. [PMID: 30240265 DOI: 10.1103/physrevlett.121.107001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Indexed: 06/08/2023]
Abstract
Microwave measurements of the London penetration depth and critical temperature T_{c} were used to show evidence of a disordered-driven transition from s_{±} to s_{++} order parameter symmetry in optimally doped Ba(Fe_{1-x}Rh_{x})_{2}As_{2} single crystals, where disorder was induced by means of 3.5 MeV proton irradiation. Signatures of such a transition, as theoretically predicted [V. D. Efremov et al., Phys. Rev. B 84, 180512(R) (2011)PRBMDO1098-012110.1103/PhysRevB.84.180512], are found as a drop in the low-temperature values of the London penetration depth and a virtually disorder-independent superconducting T_{c}. We show how these experimental observations can be described by multiband Eliashberg calculations in which the effect of disorder is accounted for in a suitable way. To this aim, an effective two-band approach is adopted, allowing us to treat disorder in a range between the Born approximation and the unitary limit.
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Affiliation(s)
- G Ghigo
- Politecnico di Torino, Department of Applied Science and Technology, Torino 10129, Italy
- Istituto Nazionale di Fisica Nucleare, Sezione di Torino, Torino 10125, Italy
| | - D Torsello
- Politecnico di Torino, Department of Applied Science and Technology, Torino 10129, Italy
- Istituto Nazionale di Fisica Nucleare, Sezione di Torino, Torino 10125, Italy
| | - G A Ummarino
- Politecnico di Torino, Department of Applied Science and Technology, Torino 10129, Italy
- National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moskva 115409, Russia
| | - L Gozzelino
- Politecnico di Torino, Department of Applied Science and Technology, Torino 10129, Italy
- Istituto Nazionale di Fisica Nucleare, Sezione di Torino, Torino 10125, Italy
| | - M A Tanatar
- Ames Laboratory, US Department of Energy, Ames, Iowa 50011, USA
- Department of Physics & Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | - R Prozorov
- Ames Laboratory, US Department of Energy, Ames, Iowa 50011, USA
- Department of Physics & Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | - P C Canfield
- Ames Laboratory, US Department of Energy, Ames, Iowa 50011, USA
- Department of Physics & Astronomy, Iowa State University, Ames, Iowa 50011, USA
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Xie T, Wei Y, Gong D, Fennell T, Stuhr U, Kajimoto R, Ikeuchi K, Li S, Hu J, Luo H. Odd and Even Modes of Neutron Spin Resonance in the Bilayer Iron-Based Superconductor CaKFe_{4}As_{4}. PHYSICAL REVIEW LETTERS 2018; 120:267003. [PMID: 30004765 DOI: 10.1103/physrevlett.120.267003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Indexed: 06/08/2023]
Abstract
We report an inelastic neutron scattering study on the spin resonance in the bilayer iron-based superconductor CaKFe_{4}As_{4}. In contrast to its quasi-two-dimensional electron structure, three strongly L-dependent modes of spin resonance are found below T_{c}=35 K. The mode energies are below and linearly scale with the total superconducting gaps summed on the nesting hole and electron pockets, essentially in agreement with the results in cuprate and heavy fermion superconductors. This observation supports the sign-reversed Cooper pairing mechanism under multiple pairing channels and resolves the long-standing puzzles concerning the broadening and dispersive spin resonance peak in iron pnictides. More importantly, the triple resonant modes can be classified into odd and even symmetries with respect to the distance of Fe-Fe planes within the Fe-As bilayer unit. Thus, our results closely resemble those in the bilayer cuprates with nondegenerate spin excitations, suggesting that these two high-T_{c} superconducting families share a common nature.
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Affiliation(s)
- Tao Xie
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yuan Wei
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Dongliang Gong
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Tom Fennell
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institute, CH-5232 Villigen, Switzerland
| | - Uwe Stuhr
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institute, CH-5232 Villigen, Switzerland
| | - Ryoichi Kajimoto
- Materials and Life Science Division, J-PARC Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
| | - Kazuhiko Ikeuchi
- Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society, Tokai, Ibaraki 319-1106, Japan
| | - Shiliang Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100190, China
| | - Jiangping Hu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100190, China
| | - Huiqian Luo
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
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