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Golod T, Morlet-Decarnin L, Krasnov VM. Word and bit line operation of a 1 × 1 μm 2 superconducting vortex-based memory. Nat Commun 2023; 14:4926. [PMID: 37582835 PMCID: PMC10427686 DOI: 10.1038/s41467-023-40654-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 08/01/2023] [Indexed: 08/17/2023] Open
Abstract
The lack of dense random access memory is one of the main bottlenecks for the creation of a digital superconducting computer. In this work we study experimentally vortex-based superconducting memory cells. Three main results are obtained. First, we test scalability and demonstrate that the cells can be straightforwardly miniaturized to submicron sizes. Second, we emphasize the importance of conscious geometrical engineering. In the studied devices we introduce an asymmetric easy track for vortex motion and show that it enables a controllable manipulation of vortex states. Finally, we perform a detailed analysis of word and bit line operation of a 1 × 1 μm2 cell. High-endurance, non-volatile operation at zero magnetic field is reported. Remarkably, we observe that the combined word and bit line threshold current is significantly reduced compared to the bare word-line operation. This could greatly improve the selectivity of individual cell addressing in a multi-cell RAM. The achieved one square micron area is an important milestone and a significant step forward towards creation of a dense cryogenic memory.
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Affiliation(s)
- Taras Golod
- Department of Physics, Stockholm University, AlbaNova University Center, SE-10691, Stockholm, Sweden
| | - Lise Morlet-Decarnin
- 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.
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2
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Thakur S, Tamarat P, Rochet A, Birk J, Veshchunov IS, Bezard M, Buzdin AI, Trebbia JB, Lounis B. High-resolution optical imaging of single magnetic flux quanta with a solid immersion lens. OPTICS EXPRESS 2023; 31:24194-24202. [PMID: 37475252 DOI: 10.1364/oe.494474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Accepted: 05/25/2023] [Indexed: 07/22/2023]
Abstract
Magneto-optical imaging of quantized magnetic flux tubes in superconductors - Abrikosov vortices - is based on Faraday rotation of light polarization within a magneto-optical indicator placed on top of the superconductor. Due to severe aberrations induced by the thick indicator substrate, the spatial resolution of vortices is usually well beyond the optical diffraction limit. Using a high refractive index solid immersion lens placed onto the indicator garnet substrate, we demonstrate wide field optical imaging of single flux quanta in a Niobium film with a resolution better than 600 nm and sub-second acquisition periods, paving the way to high-precision and fast vortex manipulation. Vectorial field simulations are also performed to reproduce and optimize the experimental features of vortex images.
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Gupta M, Graziano GV, Pendharkar M, Dong JT, Dempsey CP, Palmstrøm C, Pribiag VS. Gate-tunable superconducting diode effect in a three-terminal Josephson device. Nat Commun 2023; 14:3078. [PMID: 37248246 DOI: 10.1038/s41467-023-38856-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Accepted: 05/11/2023] [Indexed: 05/31/2023] Open
Abstract
The phenomenon of non-reciprocal critical current in a Josephson device, termed the Josephson diode effect, has garnered much recent interest. Realization of the diode effect requires inversion symmetry breaking, typically obtained by spin-orbit interactions. Here we report observation of the Josephson diode effect in a three-terminal Josephson device based upon an InAs quantum well two-dimensional electron gas proximitized by an epitaxial aluminum superconducting layer. We demonstrate that the diode efficiency in our devices can be tuned by a small out-of-plane magnetic field or by electrostatic gating. We show that the Josephson diode effect in these devices is a consequence of the artificial realization of a current-phase relation that contains higher harmonics. We also show nonlinear DC intermodulation and simultaneous two-signal rectification, enabled by the multi-terminal nature of the devices. Furthermore, we show that the diode effect is an inherent property of multi-terminal Josephson devices, establishing an immediately scalable approach by which potential applications of the Josephson diode effect can be realized, agnostic to the underlying material platform. These Josephson devices may also serve as gate-tunable building blocks in designing topologically protected qubits.
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Affiliation(s)
- Mohit Gupta
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Gino V Graziano
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Mihir Pendharkar
- Electrical and Computer Engineering, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
- Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Jason T Dong
- Materials Department, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Connor P Dempsey
- Electrical and Computer Engineering, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Chris Palmstrøm
- Electrical and Computer Engineering, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
- Materials Department, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
- California NanoSystems Institute, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Vlad S Pribiag
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, 55455, USA.
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Stolyarov VS, Ruzhitskiy V, Hovhannisyan RA, Grebenchuk S, Shishkin AG, Skryabina OV, Golovchanskiy IA, Golubov AA, Klenov NV, Soloviev II, Kupriyanov MY, Andriyash A, Roditchev D. Revealing Josephson Vortex Dynamics in Proximity Junctions below Critical Current. NANO LETTERS 2022; 22:5715-5722. [PMID: 35820103 DOI: 10.1021/acs.nanolett.2c00647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Made of a thin non-superconducting metal (N) sandwiched by two superconductors (S), SNS Josephson junctions enable novel quantum functionalities by mixing up the intrinsic electronic properties of N with the superconducting correlations induced from S by proximity. Electronic properties of these devices are governed by Andreev quasiparticles (Andreev, A. Sov. Phys. JETP 1965, 20, 1490) which are absent in conventional SIS junctions whose insulating barrier (I) between the two S electrodes owns no electronic states. Here we focus on the Josephson vortex (JV) motion inside Nb-Cu-Nb proximity junctions subject to electric currents and magnetic fields. The results of local (magnetic force microscopy) and global (transport) experiments provided simultaneously are compared with our numerical model, revealing the existence of several distinct dynamic regimes of the JV motion. One of them, identified as a fast hysteretic entry/escape below the critical value of Josephson current, is analyzed and suggested for low-dissipative logic and memory elements.
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Affiliation(s)
- Vasily S Stolyarov
- Advanced Mesoscience and Nanotechnology Centre, Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Russia
- Dukhov Research Institute of Automatics (VNIIA), 127055 Moscow, Russia
- National University of Science and Technology MISIS, 119049 Moscow, Russia
| | - Vsevolod Ruzhitskiy
- Dukhov Research Institute of Automatics (VNIIA), 127055 Moscow, Russia
- National University of Science and Technology MISIS, 119049 Moscow, Russia
| | - Razmik A Hovhannisyan
- Advanced Mesoscience and Nanotechnology Centre, Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Russia
| | - Sergey Grebenchuk
- Advanced Mesoscience and Nanotechnology Centre, Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Russia
| | - Andrey G Shishkin
- Advanced Mesoscience and Nanotechnology Centre, Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Russia
- Dukhov Research Institute of Automatics (VNIIA), 127055 Moscow, Russia
- National University of Science and Technology MISIS, 119049 Moscow, Russia
| | - Olga V Skryabina
- Advanced Mesoscience and Nanotechnology Centre, Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Russia
- National University of Science and Technology MISIS, 119049 Moscow, Russia
- Institute of Solid State Physics RAS, 142432 Chernogolovka, Russia
| | - Igor A Golovchanskiy
- Advanced Mesoscience and Nanotechnology Centre, Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Russia
- Dukhov Research Institute of Automatics (VNIIA), 127055 Moscow, Russia
- National University of Science and Technology MISIS, 119049 Moscow, Russia
| | - Alexander A Golubov
- Faculty of Science and Technology, MESA+ Institute of Nanotechnology, 7500 AE Enschede, The Netherlands
| | - Nikolay V Klenov
- Dukhov Research Institute of Automatics (VNIIA), 127055 Moscow, Russia
- National University of Science and Technology MISIS, 119049 Moscow, Russia
- Faculty of Physics, Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Igor I Soloviev
- Dukhov Research Institute of Automatics (VNIIA), 127055 Moscow, Russia
- National University of Science and Technology MISIS, 119049 Moscow, Russia
- Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Mikhail Yu Kupriyanov
- National University of Science and Technology MISIS, 119049 Moscow, Russia
- Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, 119991 Moscow, Russia
| | | | - Dimitri Roditchev
- LPEM, ESPCI Paris, PSL Research University, CNRS, 75005 Paris, France
- Sorbonne Universite, CNRS, LPEM, 75005 Paris, France
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Golod T, Krasnov VM. Demonstration of a superconducting diode-with-memory, operational at zero magnetic field with switchable nonreciprocity. Nat Commun 2022; 13:3658. [PMID: 35760801 PMCID: PMC9237109 DOI: 10.1038/s41467-022-31256-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 06/10/2022] [Indexed: 11/09/2022] Open
Abstract
Diode is one of the basic electronic components. It has a nonreciprocal current response, associated with a broken space/time reversal symmetry. Here we demonstrate prototypes of superconducting diodes operational at zero magnetic field. They are based on conventional niobium planar Josephson junctions, in which space/time symmetry is broken by a combination of self-field effect from nonuniform bias and stray fields from a trapped Abrikosov vortex. We demonstrate that nonreciprocity of critical current in such diodes can reach an order of magnitude and rectification efficiency can exceed 70%. Furthermore, we can easily change the diode polarity and switch nonreciprocity on/off by changing the bias configuration and by trapping/removing of a vortex. This facilitates a memory functionality. We argue that such a diode-with-memory can be used for a future generation of in-memory superconducting computers.
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Affiliation(s)
- Taras Golod
- 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.
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Hovhannisyan RA, Grebenchuk SY, Baranov DS, Roditchev D, Stolyarov VS. Lateral Josephson Junctions as Sensors for Magnetic Microscopy at Nanoscale. J Phys Chem Lett 2021; 12:12196-12201. [PMID: 34918928 DOI: 10.1021/acs.jpclett.1c03556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Lateral Josephson junctions (LJJ) made of two superconducting Nb electrodes coupled by Cu-film are applied to quantify the stray magnetic field of Co-coated cantilevers used in magnetic force microscopy (MFM). The interaction of the magnetic cantilever with LJJ is reflected in the electronic response of LJJ as well as in the phase shift of cantilever oscillations, simultaneously measured. The phenomenon is theorized and used to establish the spatial map of the stray field. Based on our findings, we suggest integrating LJJs directly on the tips of cantilevers and using them as nanosensors of local magnetic fields in scanning probe microscopes. Such probes are less invasive than conventional magnetic MFM cantilevers and simpler to realize than SQUID-on-tip sensors.
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Affiliation(s)
- Razmik A Hovhannisyan
- Advanced mesoscience and nanotechnology centre, Moscow Institute of Physics and Technology, Dolgoprudny 141700, Russia
- Department of Physics, Stockholm University, AlbaNova University Center, SE-10691 Stockholm, Sweden
| | - Sergey Yu Grebenchuk
- Advanced mesoscience and nanotechnology centre, Moscow Institute of Physics and Technology, Dolgoprudny 141700, Russia
- Department of Materials Science and Engineering, National University of Singapore, 117575, Singapore, Singapore
| | - Denis S Baranov
- Advanced mesoscience and nanotechnology centre, Moscow Institute of Physics and Technology, Dolgoprudny 141700, Russia
- Dukhov Research Institute of Automatics (VNIIA), 127055 Moscow, Russia
- National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), 115409 Moscow, Russia
| | - Dimitri Roditchev
- LPEM UMR-8213, ESPCI Paris, PSL Research University, CNRS, 75005 Paris, France
- INSP UMR-7588, Sorbonne Universite, CNRS, 75005 Paris, France
| | - Vasily S Stolyarov
- Advanced mesoscience and nanotechnology centre, Moscow Institute of Physics and Technology, Dolgoprudny 141700, Russia
- Dukhov Research Institute of Automatics (VNIIA), 127055 Moscow, Russia
- National University of Science and Technology MISIS, Moscow 119049, Russia
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7
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Superconducting Properties and Electron Scattering Mechanisms in a Nb Film with a Single Weak-Link Excavated by Focused Ion Beam. MATERIALS 2021; 14:ma14237274. [PMID: 34885429 PMCID: PMC8658209 DOI: 10.3390/ma14237274] [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: 10/24/2021] [Revised: 11/18/2021] [Accepted: 11/20/2021] [Indexed: 11/16/2022]
Abstract
Granularity is one of the main features restricting the maximum current which a superconductor can carry without losses, persisting as an important research topic when applications are concerned. To directly observe its effects on a typical thin superconducting specimen, we have modeled the simplest possible granular system by fabricating a single artificial weak-link in the center of a high-quality Nb film using the focused ion beam technique. Then, its microstructural, magnetic, and electric properties in both normal and superconducting states were studied. AC susceptibility, DC magnetization, and magneto-transport measurements reveal well-known granularity signatures and how they negatively affect superconductivity. Moreover, we also investigate the normal state electron scattering mechanisms in the Boltzmann theory framework. The results clearly demonstrate the effect of the milling technique, giving rise to an additional quadratic-in-temperature contribution to the usual cubic-in-temperature sd band scattering for the Nb film. Finally, by analyzing samples with varying density of incorporated defects, the emergence of the additional contribution is correlated to a decrease in their critical temperature, in agreement with recent theoretical results.
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