People
Graduate Student
Andrei Kudriashov
Title
PhD Student
Research Interests
Topological insulators, superconductivity
Research Group
Office Location
S9-08-01-36
I-FIM Publications:
2025 |
Kudriashov, A; Hovhannisyan, R A; Zhou, X; Elesin, L; Yashina, L V; Novoselov, K S; Bandurin, D A Reconstructing critical current density in Josephson junctions with phase nonlinearity PHYSICAL REVIEW B, 112 (6), 2025, DOI: 10.1103/lgpj-wy72. @article{WOS:001553737700001, title = {Reconstructing critical current density in Josephson junctions with phase nonlinearity}, author = {A Kudriashov and R A Hovhannisyan and X Zhou and L Elesin and L V Yashina and K S Novoselov and D A Bandurin}, doi = {10.1103/lgpj-wy72}, times_cited = {1}, issn = {2469-9950}, year = {2025}, date = {2025-08-01}, journal = {PHYSICAL REVIEW B}, volume = {112}, number = {6}, publisher = {AMER PHYSICAL SOC}, address = {ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA}, abstract = {In this Letter, we show that the standard Dynes-Fulton analysis, commonly used to reconstruct the critical current density from interference patterns, breaks down in Josephson junctions with nonlinear phase distributions, leading to nonphysical artifacts. To address this, we developed a simple iterative reconstruction algorithm and validated it both numerically and experimentally using a planar Josephson junction model. Unlike conventional approaches based on the logarithmic Hilbert transform, the proposed method allows for incorporating prior knowledge about the system and addresses the fundamental issue of ambiguity in reconstructing the critical current density from interference patterns.}, keywords = {}, pubstate = {published}, tppubtype = {article} } In this Letter, we show that the standard Dynes-Fulton analysis, commonly used to reconstruct the critical current density from interference patterns, breaks down in Josephson junctions with nonlinear phase distributions, leading to nonphysical artifacts. To address this, we developed a simple iterative reconstruction algorithm and validated it both numerically and experimentally using a planar Josephson junction model. Unlike conventional approaches based on the logarithmic Hilbert transform, the proposed method allows for incorporating prior knowledge about the system and addresses the fundamental issue of ambiguity in reconstructing the critical current density from interference patterns.
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Kudriashov, Andrei; Zhou, Xiangyu; Hovhannisyan, Razmik A; Frolov, Alexander S; Elesin, Leonid; Wang, Yi Bo; Zharkova, Ekaterina V; Taniguchi, Takashi; Watanabe, Kenji; Liu, Zheng; Novoselov, Kostya S; Yashina, Lada V; Zhou, Xin; Bandurin, Denis A Non-Majorana origin of anomalous current-phase relation and Josephson diode effect in Bi2SE3/NbSe2 Josephson junctions SCIENCE ADVANCES, 11 (24), 2025, DOI: 10.1126/sciadv.adw6925. @article{WOS:001508114400008, title = {Non-Majorana origin of anomalous current-phase relation and Josephson diode effect in Bi2SE3/NbSe2 Josephson junctions}, author = {Andrei Kudriashov and Xiangyu Zhou and Razmik A Hovhannisyan and Alexander S Frolov and Leonid Elesin and Yi Bo Wang and Ekaterina V Zharkova and Takashi Taniguchi and Kenji Watanabe and Zheng Liu and Kostya S Novoselov and Lada V Yashina and Xin Zhou and Denis A Bandurin}, doi = {10.1126/sciadv.adw6925}, times_cited = {7}, year = {2025}, date = {2025-06-01}, journal = {SCIENCE ADVANCES}, volume = {11}, number = {24}, publisher = {AMER ASSOC ADVANCEMENT SCIENCE}, address = {1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA}, abstract = {Josephson junctions (JJs) are key to superconducting quantum technologies and the search for self-conjugate quasiparticles potentially useful for fault-tolerant quantum computing. In topological insulator (TI)-based JJs, measuring the current-phase relation (CPR) can reveal unconventional effects such as Majorana bound states (MBS) and nonreciprocal transport. However, reconstructing CPR as a function of magnetic field has not been attempted. Here, we present a platform for field-dependent CPR measurements in planar JJs made of NbSe2 and few-layer Bi2Se3. When a flux quantum Phi 0 threads the junction, we observe anomalous peak-dip CPR structure and nonreciprocal supercurrent flow. We show that these arise from a nonuniform supercurrent distribution that also leads to a robust and tunable Josephson diode effect. Furthermore, despite numerous previous studies, we find no evidence of MBS. Our results establish magnetic field-dependent CPR as a powerful probe of TI-based superconducting devices and offer design strategies for nonreciprocal superconducting electronics.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Josephson junctions (JJs) are key to superconducting quantum technologies and the search for self-conjugate quasiparticles potentially useful for fault-tolerant quantum computing. In topological insulator (TI)-based JJs, measuring the current-phase relation (CPR) can reveal unconventional effects such as Majorana bound states (MBS) and nonreciprocal transport. However, reconstructing CPR as a function of magnetic field has not been attempted. Here, we present a platform for field-dependent CPR measurements in planar JJs made of NbSe2 and few-layer Bi2Se3. When a flux quantum Phi 0 threads the junction, we observe anomalous peak-dip CPR structure and nonreciprocal supercurrent flow. We show that these arise from a nonuniform supercurrent distribution that also leads to a robust and tunable Josephson diode effect. Furthermore, despite numerous previous studies, we find no evidence of MBS. Our results establish magnetic field-dependent CPR as a powerful probe of TI-based superconducting devices and offer design strategies for nonreciprocal superconducting electronics.
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Kravtsov, M; Shilov, A L; Yang, Y; Pryadilin, T; Kashchenko, M A; Popova, O; Titova, M; Voropaev, D; Wang, Y; Shein, K; Gayduchenko, I; Goltsman, G N; Lukianov, M; Kudriashov, A; Taniguchi, T; Watanabe, K; Svintsov, D A; Adam, S; Novoselov, K S; Principi, A; Bandurin, D A Viscous terahertz photoconductivity of hydrodynamic electrons in graphene 13 NATURE NANOTECHNOLOGY, 20 (1), pp. 51+, 2025, DOI: 10.1038/s41565-024-01795-y. @article{WOS:001330508900002, title = {Viscous terahertz photoconductivity of hydrodynamic electrons in graphene}, author = {M Kravtsov and A L Shilov and Y Yang and T Pryadilin and M A Kashchenko and O Popova and M Titova and D Voropaev and Y Wang and K Shein and I Gayduchenko and G N Goltsman and M Lukianov and A Kudriashov and T Taniguchi and K Watanabe and D A Svintsov and S Adam and K S Novoselov and A Principi and D A Bandurin}, doi = {10.1038/s41565-024-01795-y}, times_cited = {13}, issn = {1748-3387}, year = {2025}, date = {2025-01-01}, journal = {NATURE NANOTECHNOLOGY}, volume = {20}, number = {1}, pages = {51+}, publisher = {NATURE PORTFOLIO}, address = {HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY}, abstract = {Light incident upon materials can induce changes in their electrical conductivity, a phenomenon referred to as photoresistance. In semiconductors, the photoresistance is negative, as light-induced promotion of electrons across the bandgap enhances the number of charge carriers participating in transport. In superconductors and normal metals, the photoresistance is positive because of the destruction of the superconducting state and enhanced momentum-relaxing scattering, respectively. Here we report a qualitative deviation from the standard behaviour in doped metallic graphene. We show that Dirac electrons exposed to continuous-wave terahertz (THz) radiation can be thermally decoupled from the lattice, which activates hydrodynamic electron transport. In this regime, the resistance of graphene constrictions experiences a decrease caused by the THz-driven superballistic flow of correlated electrons. We analyse the dependencies of the negative photoresistance on the carrier density, and the radiation power, and show that our superballistic devices operate as sensitive phonon-cooled bolometers and can thus offer, in principle, a picosecond-scale response time. Beyond their fundamental implications, our findings underscore the practicality of electron hydrodynamics in designing ultra-fast THz sensors and electron thermometers.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Light incident upon materials can induce changes in their electrical conductivity, a phenomenon referred to as photoresistance. In semiconductors, the photoresistance is negative, as light-induced promotion of electrons across the bandgap enhances the number of charge carriers participating in transport. In superconductors and normal metals, the photoresistance is positive because of the destruction of the superconducting state and enhanced momentum-relaxing scattering, respectively. Here we report a qualitative deviation from the standard behaviour in doped metallic graphene. We show that Dirac electrons exposed to continuous-wave terahertz (THz) radiation can be thermally decoupled from the lattice, which activates hydrodynamic electron transport. In this regime, the resistance of graphene constrictions experiences a decrease caused by the THz-driven superballistic flow of correlated electrons. We analyse the dependencies of the negative photoresistance on the carrier density, and the radiation power, and show that our superballistic devices operate as sensitive phonon-cooled bolometers and can thus offer, in principle, a picosecond-scale response time. Beyond their fundamental implications, our findings underscore the practicality of electron hydrodynamics in designing ultra-fast THz sensors and electron thermometers.
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2024 |
Shilov, Artur L; Kashchenko, Mikhail A; Peralta, Pierre Pantaleon A; Wang, Yibo; Kravtsov, Mikhail; Kudriashov, Andrei; Zhan, Zhen; Taniguchi, Takashi; Watanabe, Kenji; Slizovskiy, Sergey; Novoselov, Kostya S; Fal'ko, Vladimir I; Guinea, Francisco; Bandurin, Denis A High-Mobility Compensated Semimetals, Orbital Magnetization, and Umklapp Scattering in Bilayer Graphene Moire Superlattices ACS NANO, 18 (18), pp. 11769-11777, 2024, DOI: 10.1021/acsnano.3c13212. @article{WOS:001226272500001, title = {High-Mobility Compensated Semimetals, Orbital Magnetization, and Umklapp Scattering in Bilayer Graphene Moire Superlattices}, author = {Artur L Shilov and Mikhail A Kashchenko and Pierre Pantaleon A Peralta and Yibo Wang and Mikhail Kravtsov and Andrei Kudriashov and Zhen Zhan and Takashi Taniguchi and Kenji Watanabe and Sergey Slizovskiy and Kostya S Novoselov and Vladimir I Fal'ko and Francisco Guinea and Denis A Bandurin}, doi = {10.1021/acsnano.3c13212}, times_cited = {6}, issn = {1936-0851}, year = {2024}, date = {2024-04-01}, journal = {ACS NANO}, volume = {18}, number = {18}, pages = {11769-11777}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {Twist-controlled moire superlattices (MSs) have emerged as a versatile platform for realizing artificial systems with complex electronic spectra. The combination of Bernal-stacked bilayer graphene (BLG) and hexagonal boron nitride (hBN) can give rise to an interesting MS, which has recently featured a set of unexpected behaviors, such as unconventional ferroelectricity and the electronic ratchet effect. Yet, the understanding of the electronic properties of BLG/hBN MS has, at present, remained fairly limited. Here, we combine magneto-transport and low-energy sub-THz excitation to gain insights into the properties of this MS. We demonstrate that the alignment between BLG and hBN crystal lattices results in the emergence of compensated semimetals at some integer fillings of the moire bands, separated by van Hove singularities where the Lifshitz transition occurs. A particularly pronounced semimetal develops when eight holes reside in the moire unit cell, where coexisting high-mobility electron and hole systems feature strong magnetoresistance reaching 2350% already at B = 0.25 T. Next, by measuring the THz-driven Nernst effect in remote bands, we observe valley splitting, indicating an orbital magnetization characterized by a strongly enhanced effective g(v)-factor of 340. Finally, using THz photoresistance measurements, we show that the high-temperature conductivity of the BLG/hBN MS is limited by electron-electron umklapp processes. Our multifaceted analysis introduces THz-driven magnetotransport as a convenient tool to probe the band structure and interaction effects in van der Waals materials and provides a comprehensive understanding of the BLG/hBN MS.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Twist-controlled moire superlattices (MSs) have emerged as a versatile platform for realizing artificial systems with complex electronic spectra. The combination of Bernal-stacked bilayer graphene (BLG) and hexagonal boron nitride (hBN) can give rise to an interesting MS, which has recently featured a set of unexpected behaviors, such as unconventional ferroelectricity and the electronic ratchet effect. Yet, the understanding of the electronic properties of BLG/hBN MS has, at present, remained fairly limited. Here, we combine magneto-transport and low-energy sub-THz excitation to gain insights into the properties of this MS. We demonstrate that the alignment between BLG and hBN crystal lattices results in the emergence of compensated semimetals at some integer fillings of the moire bands, separated by van Hove singularities where the Lifshitz transition occurs. A particularly pronounced semimetal develops when eight holes reside in the moire unit cell, where coexisting high-mobility electron and hole systems feature strong magnetoresistance reaching 2350% already at B = 0.25 T. Next, by measuring the THz-driven Nernst effect in remote bands, we observe valley splitting, indicating an orbital magnetization characterized by a strongly enhanced effective g(v)-factor of 340. Finally, using THz photoresistance measurements, we show that the high-temperature conductivity of the BLG/hBN MS is limited by electron-electron umklapp processes. Our multifaceted analysis introduces THz-driven magnetotransport as a convenient tool to probe the band structure and interaction effects in van der Waals materials and provides a comprehensive understanding of the BLG/hBN MS.
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