arXiv subjects

Mikhail Yu. Kupriyanov

Publications and source records attributed to Mikhail Yu. Kupriyanov.

5 recordsLinked to original sources

arXiv2023

Josephson vortex-based memory

Josephson junctions are currently used as base elements of superconducting logic systems. Long enough junctions subject to magnetic field host quantum phase 2π-singularities - Josephson vortices. Here we report the realization of the superconducting memory whose state is encoded by the number of present Josephson vortices. By integrating the junction into a coplanar resonator and by applying a microwave excitation well below the critical current, we were able to control the state of the memory in an energy-efficent and non-destructive manner. The performance of the device is evaluated, and the routes for creating scalable cryogenic memories directly compatible with superconducting microwave technologies are discussed.

cond-mat.supr-con↗

arXiv2022

Revealing intrinsic superconductivity of the Nb/BiSbTe$_2$Se interface

Typically, topological superconductivity is reachable via proximity effect by a direct deposition of superconductor (S) on top of a topological insulator (TI) surface. Here we observed and analyzed the double critical current in the Josephson junctions based on the topological insulator in the fabricated planar Superconducting Quantum Interference Device. By measuring critical currents as a function of temperature and magnetic field, we show that the second critical current stems from the intrinsic superconductivity of the S/TI interface, which is supported by the modified Resistively Shunted Junction model and Transmission Electron Microscopy studies. This complex structure of the interface should be taken into account when technological process involves Ar-plasma cleaning.

cond-mat.supr-con↗

arXiv2022

Revealing Josephson vortex dynamics in proximity junctions below critical current

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 [1] 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.

cond-mat.supr-con↗

arXiv2012

Magnetic Josephson Junctions with Superconducting Interlayer for Cryogenic Memory

We investigate Magnetic Josephson Junction (MJJ) - a superconducting device with ferromagnetic barrier for a scalable high-density cryogenic memory compatible with energy-efficient single flux quantum (SFQ) circuits. The superconductor-insulator-superconductor-ferromagnet-superconductor (SIS'FS) MJJs are analyzed both experimentally and theoretically. We found that the properties of SIS'FS junctions fall into two distinct classes based on the thickness of S' layer. We fabricate Nb-Al/AlOx-Nb-PdFe-Nb SIS'FS MJJs using a co-processing approach with a combination of HYPRES and ISSP fabrication processes. The resultant SIS'FS structure with thin superconducting S'-layer is substantially affected by the ferromagnetic layer as a whole. We fabricate these type of junctions to reach the device compatibility with conventional SIS junctions used for superconducting SFQ electronics to ensure a seamless integration of MJJ-based circuits and SIS JJ-based ultra-fast digital SFQ circuits. We report experimental results for MJJs, demonstrating their applicability for superconducting memory and digital circuits. These MJJs exhibit IcRn product only ~30% lower than that of conventional SIS junctions co-produced in the same fabrication. Analytical calculations for these SIS'FS structures are in a good agreement with the experiment. We discuss application of MJJ devices for memory and programmable logic circuits.

cond-mat.supr-con↗

arXiv2012

Double proximity effect in hybrid planar Superconductor-(Normal metal/Ferromagnet)-Superconductor structures

We have investigated the differential resistance of hybrid planar Al-(Cu/Fe)-Al submicron bridges at low temperatures and in weak magnetic fields. The structure consists of Cu/Fe-bilayer forming a bridge between two superconducting Al-electrodes. In superconducting state of Al-electrodes, we have observed a double-peak peculiarity in differential resistance of the S-(N/F)-S structures at a bias voltage corresponding to the minigap. We claim that this effect (the doubling of the minigap) is due to an electron spin polarization in the normal metal which is induced by the ferromagnet. We have demonstrated that the double-peak peculiarity is converted to a single peak at a coercive applied field corresponding to zero magnetization of the Fe-layer.

cond-mat.supr-con↗