Article
Chemistry, Multidisciplinary
Damon James Carrad, Lukas Stampfer, Dags Olsteins, Christian Emmanuel Noes Petersen, Sabbir A. Khan, Peter Krogstrup, Thomas Sand Jespersen
Summary: Semiconductor/superconductor hybrids have been studied to explore novel physics and develop new technologies. In this study, Josephson junctions defined by shadow epitaxy on InAsSb/Al nanowires were investigated. The devices exhibited gate-tunable supercurrents at low temperatures and multiple Andreev reflections at finite voltage bias. Under microwave irradiation, characteristic oscillating sidebands at quantized energies were observed, which confirmed a recently suggested modification of a classical equation. The measurements provided evidence for the effective charge transferred by the tunneling process and suggested photon-assisted tunneling as a powerful method for identifying low-energy spectral features in hybrid Josephson devices.
Article
Materials Science, Multidisciplinary
Shu-Chang Zhao, Lu Gao, Qiang Cheng, Qing-Feng Sun
Summary: This study investigates the crossed Andreev reflection and nonlocal transport in proximitized graphene/superconductor/proximitized graphene junctions with pseudospin staggered potential and intrinsic spin-orbit coupling. When the intrinsic spin-orbit couplings in the left and right graphene have opposite signs, the crossed Andreev reflection, coexisting with the local Andreev reflection and elastic cotunneling, can be completely eliminated for electrons with specific spin-valley indices. A perfect crossed Andreev reflection with a probability of 100% is achieved in the space of incident angle and electron energy. The crossed conductance and its dependence on superconductor length are also investigated. The energy ranges for the crossed Andreev reflection, without the local Andreev reflection and elastic cotunneling, are clarified for different magnitudes of the pseudospin potential and spin-orbit coupling. The spin-valley index of electrons responsible for the perfect crossed Andreev reflection can be controlled by changing the sign of the intrinsic spin-orbit coupling or applying different biases to the left and right graphene. These results are useful for designing flexible and highly efficient Cooper pair splitters based on spin-valley degree of freedom.
Article
Materials Science, Multidisciplinary
Lu Gao, Qiang Cheng, Qing-Feng Sun
Summary: In this study, we investigate the Andreev reflections and quantum transport in the proximitized graphene/superconductor junction. We find that the presence of pseudospin staggered potential and intrinsic spin-orbit coupling in the junction leads to spin-valley dependent double Andreev reflections and anomalous transport properties. These spin-valley dependent Andreev reflections offer a way to detect the induced potential and coupling in graphene and establish the foundation of superconductor electronics based on spin-valley indices.
Article
Chemistry, Multidisciplinary
Shili Yan, Haitian Su, Dong Pan, Weijie Li, Zhaozheng Lyu, Mo Chen, Xingjun Wu, Li Lu, Jianhua Zhao, Ji-Yin Wang, Hongqi Xu
Summary: We conducted an experimental study on proximity-induced superconductivity in planar Josephson junction devices using free-standing InAs nanosheets. The nanosheets were grown by molecular beam epitaxy, and the devices were fabricated by directly contacting the nanosheets with Al electrodes. Low-temperature measurements showed gate-tunable supercurrent, multiple Andreev reflections, and a good quality superconductor-semiconductor interface. The superconducting characteristics of the Josephson junctions were analyzed based on the BCS theory at different magnetic fields and temperatures. The ac Josephson effect measurements under microwave radiation revealed the observation of integer Shapiro steps. This work demonstrates the potential of InAs nanosheet-based hybrid devices for exploring the forefront of physics, such as two-dimensional topological superconductivity.
Article
Physics, Multidisciplinary
Shahrukh Salim, Rahul Marathe, Sankalpa Ghosh
Summary: In this study, we compare the theory with experimental results on charge transport through Josephson junctions made of graphene. A transfer matrix approach is used to analytically derive the spectrum of Andreev bound states (ABS) in a superconductor-graphene-superconductor junction, focusing on monolayer graphene. The theoretical results successfully explain both the retro Andreev reflection (RAR) and specular Andreev reflection (SAR) phenomena within the relevant parameter range. By evaluating the current and conductance using the ABS spectrum and experimental system parameters, we find good agreement with experimental results, with the calculated values showing scaling behavior with junction length and significantly lower values when RAR is dominant.
Article
Physics, Applied
Tobias W. Schmitt, Benedikt Frohn, Wilhelm Wittl, Abdur R. Jalil, Michael Schleenvoigt, Erik Zimmermann, Anne Schmidt, Thomas Schaepers, Juan Carlos Cuevas, Alexander Brinkman, Detlev Gruetzmacher, Peter Schueffelgen
Summary: In this study, the temperature-dependent behavior of a Bi2Te3-based Josephson junction (JJ) with transparent interfaces is investigated, providing insights into the contributions of bulk and surface states in topological insulator JJs. Differential conductance spectra of multiple Andreev reflections (MARs) are measured in electrical transport experiments, showing a qualitative temperature-dependent change from peak features to dip features. The observation of both types of MAR patterns in a single JJ suggests the presence of diffusive bulk and ballistic surface states, and their connection to the temperature dependence of the critical current. This work advances the understanding of induced superconductivity in topological insulators and offers new avenues for studying induced superconductivity in the topological surface states of these materials.
SUPERCONDUCTOR SCIENCE & TECHNOLOGY
(2023)
Article
Physics, Applied
Xue Yang, Pablo Burset, Bo Lu
Summary: In a four-terminal setup, researchers found that a quantum spin Hall strip with different edges contacted by s-wave superconductors can exhibit Majorana bound states protected by time-reversal symmetry. They observed a subharmonic gap structure in the conductance peaks from multiple Andreev reflections, which is sensitive to the phase difference between the superconductors. This phase difference also controls an even-odd effect, where odd spikes disappear and even spikes split when the Majorana states form or when the superconductors have different gap sizes.
SUPERCONDUCTOR SCIENCE & TECHNOLOGY
(2023)
Article
Materials Science, Multidisciplinary
Rak-Hee Kim, Nam-Hee Kim, Bongkeon Kim, Yasen Hou, Dong Yu, Yong-Joo Doh
Summary: Superconducting proximity junctions made of topological insulator nanoribbons offer a useful platform for studying topological superconductivity. In this study, Josephson junctions using Sb-doped Bi2Se3 nanoribbons in contact with Al electrodes were fabricated and measured. The observations of Aharonov-Bohm and Altshuler-Aronov-Spivak oscillations in the axial magneto-conductance of the nanoribbons indicate the presence of metallic surface states.
CURRENT APPLIED PHYSICS
(2022)
Article
Physics, Multidisciplinary
Qiang-Tao Sui, Xiang-Gang Qui
Summary: In this study of the iron-based superconductor Ca-10(Pt3As8)((Fe0.9Pt0.1)(2)As-2)(5), a crossover from Abrikosov vortices to Josephson vortices at a certain temperature is observed. This crossover is confirmed by abnormal behaviors of critical current and flux-flow resistance. The findings indicate the presence of intrinsic Josephson junctions and quasi-two-dimensional superconductivity in Ca-10(Pt3As8)((Fe0.9Pt0.1)(2)As-2)(5), similar to cuprate superconductors.
Article
Physics, Condensed Matter
Shu-feng Zhang, Tian-yi Zhang
Summary: The electronic transport properties of a 2D normal metal superconductor were studied, revealing changes in Andreev reflection under different disorder regimes, with an explanation of the underlying mechanism.
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS
(2021)
Article
Physics, Applied
Ko-Fan Huang, Onder Gul, Takashi Taniguchi, Kenji Watanabe, Philip Kim
Summary: We present planar aluminum superconductor-graphene junctions with a hybrid interface engineered for various couplings. The use of an atomically thin van der Waals tunneling barrier allows for couplings ranging from tunneling to the strongly coupled regime. The junction characteristics can be controlled by the choice of barrier material, with hexagonal boron nitride (hBN) resulting in weak coupling and monolayer transition metal dichalcogenides (TMDs) leading to intermediate coupling with enhanced conductance.
LOW TEMPERATURE PHYSICS
(2023)
Article
Multidisciplinary Sciences
Svetoslav Kuzmichev, Tatiana Kuzmicheva, Igor Morozov, Alexander Boltalin, Andrey Shilov
Summary: The structure of the superconducting order parameter in LiFeAs is studied using incoherent multiple Andreev reflections effect (IMARE) spectroscopy. SnS junctions show the presence of at least three bulk superconducting order parameters in LiFeAs, and we discuss their symmetry.
SN APPLIED SCIENCES
(2022)
Article
Physics, Applied
Hong Li, Xinjian Yang
Summary: The proximity effect and finite-quasi-particle-lifetime effect in normal metal/insulator/ferromagnet/f-wave superconductor structures are theoretically investigated. The conductance spectra exhibit a transition from the 0 state to pi state with increasing ferromagnetic exchange energy due the proximity effect. The choice of f-wave pairing potential leads to different tunneling conductance characteristics.
PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS
(2022)
Article
Engineering, Electrical & Electronic
Coenrad J. Fourie, Kyle Jackman
Summary: Soft defects caused by flux quanta not captured by moats during superconductor integrated circuit cooldown can degrade circuit performance. Random moat placement may not improve performance and can even decrease it. Through numerical simulation tools and experiments, it was shown that trapped flux in moats can affect the critical current of a SQUID, leading to the development of design rules.
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY
(2021)
Proceedings Paper
Acoustics
Stefano Ricci, Carmela Morizzo, Daniele Mazierli, Piero Tortoli, Michaela Kozakova, Carlo Palombo
Summary: This study investigated the differences in blood flow velocity profiles in the carotid and femoral arteries of normal subjects, as well as their correlations with systemic and local parameters. The results showed that the profile shape in the carotid arteries was mostly parabolic, while it was not in the femoral artery. It was also found that systemic hemodynamic factors had a greater impact on the carotid profile shape, while local factors were more relevant for the femoral profile.
INTERNATIONAL ULTRASONICS SYMPOSIUM (IEEE IUS 2021)
(2021)
Article
Physics, Multidisciplinary
K. S. Pervakov, L. F. Kulikova, A. Yu Tsvetkov, V. A. Vlasenko
Summary: A novel iron-based 1111-type superconductor Ca0.5Sm0.5FeAsF was synthesized in an argon atmosphere at a pressure of 50 kbar for the first time, with a superconducting transition onset temperature of 54.2 K, placing it among the highest-temperature iron-based superconductors known such as SmFeAs(F,O) and GdFeAs(F,O).
BULLETIN OF THE LEBEDEV PHYSICS INSTITUTE
(2022)
Article
Materials Science, Multidisciplinary
I. A. Golovchanskiy, E. Maltsev, I. Shchetinin, V. A. Vlasenko, P. S. Dzhumaev, K. S. Pervakov, O. Emelyanova, A. Yu Tsvetkov, N. N. Abramov, V. M. Pudalov, V. S. Stolyarov
Summary: In this study, we investigated the characteristics of EuSn2As2 single crystals at different temperatures using magnetization measurements, structural characterization, and broad-band ferromagnetic resonance spectroscopy. We observed the conventional collective acoustic resonance mode of the A-type antiferromagnetic canted state in the Eu sub-lattice, as well as its transition to the paramagnetic resonance above the ordering temperature. Additionally, we observed reproducible additional spectral line, which is associated with the magnetism in the Eu sub-lattice.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Alena Yu Degtyarenko, Igor A. Karateev, Alexey Ovcharov, Vladimir A. Vlasenko, Kirill S. Pervakov
Summary: In the stoichiometric iron-based superconductor EuRbFe4As4, two-dimensional intrinsic nanoinclusions of RbFe2As2 (122) phase were observed. These non-superconducting nanoinclusions could act as 2D pinning centers. Furthermore, no second magnetization peak was observed in the magnetization measurements at low temperature.
Article
Materials Science, Multidisciplinary
Nikita S. Pavlov, Kirill S. Pervakov, Igor A. Nekrasov
Summary: By using a first-principles DFT/GGA approach, the electronic structure, magnetism, and Fermi surface of the potential iron-based superconductor KCa2Fe4As4O2 (12442) were investigated. The self-doping value of KCa2Fe4As4O2 was found to be 0.75 hole on Fe-3d states. Surprisingly, it was observed that in addition to the Fe-3d bands, the O-2p bands also cross the Fermi level in KCa2Fe4As4O2, which is unusual for O-2p states. The presence of a metallic O-2p band in KCa2Fe4As4O2 suggests that it may be a potential superconductor with unique properties.
COMPUTATIONAL MATERIALS SCIENCE
(2023)
Article
Physics, Multidisciplinary
S. A. Kuzmichev, K. S. Pervakov, V. A. Vlasenko, A. Yu. Degtyarenko, S. Yu. Gavrilkin, T. E. Kuzmicheva
Summary: Single crystals of EuCsFe4As4 pnictide exhibit multiple-gap superconductivity under specific conditions, showing a gap structure similar to that of other pnictide materials.
Article
Physics, Multidisciplinary
N. S. Pavlov, I. R. Shein, K. S. Pervakov, I. A. Nekrasov
Summary: A comparative analysis of electronic structures of possible isostructural analogues of iron superconductors InCo2As2 and KInCo4As4 with BaFe2As2 was conducted using DFT/LDA and LDA + DMFT approaches. Results showed relatively small quasiparticle mass renormalization at the Fermi level, and significant shifts and compressions of the spectrum below -0.8 eV due to correlation effects. The band structure of InCo2As2 resembled BaCo2As2, while KInCo4As4 showed similarities with the band structure and Fermi surfaces of BaFe2As2, suggesting the possibility of superconductivity. Furthermore, LDA + DMFT calculations indicated topological Lifshitz transitions under hole or electron doping in KInCo4As4. The synthesis of InCo2As2 and KInCo4As4 compounds is crucial for studying superconductivity in this class of materials.
Article
Chemistry, Inorganic & Nuclear
Andrey I. Shilov, Kirill S. Pervakov, Konstantin A. Lyssenko, Vladimir A. Vlasenko, Dmitri V. Efremov, Saicharan Aswartham, Sergey V. Simonov, Igor V. Morozov, Andrei V. Shevelkov
Summary: We have grown and characterized four new ternary layered bismuthides, KZn2Bi2 (I), RbZn2Bi2 (II), RbCd2Bi2 (III), and CsCd2Bi2 (IV), which belong to the 122 family of compounds. Single crystals obtained by self-flux technique were analyzed using a combination of powder X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and single crystal X-ray diffraction. All compounds crystallize in the layered ThCr2Si2 structure and have a plate-like morphology with weak bonding between layers. A significant structural difference between ACd(2)Bi(2) and AZn(2)Bi(2) is observed and discussed.
ZEITSCHRIFT FUR ANORGANISCHE UND ALLGEMEINE CHEMIE
(2023)
Article
Physics, Multidisciplinary
M. V. Golubkov, V. A. Stepanov, A. V. Sadakov, A. S. Usol'tsev, I. V. Morozov
Summary: The characteristics of point Josephson contacts Pb0.6In0.4/KFe2As2 and KFe2As2/KFe2As2 were studied. The temperature dependence of characteristic contact voltages V-C(T) and the dependence of the first current step amplitudes in I-V characteristics on the power of 7.6-GHz electromagnetic radiation were measured. It was found that V-C(T) curves for all contacts can be described in terms of the SIS*IS contact model for superconductors with the s-symmetry of order parameter. It was also proven that the current step oscillation period as a function of microwave power can be approximated with the resistive model of contact with I-S = I(C)sin(phi). The obtained data are consistent with the normal s-symmetry of order parameter.
JOURNAL OF EXPERIMENTAL AND THEORETICAL PHYSICS
(2023)
Article
Physics, Multidisciplinary
T. E. Kuzmicheva, S. A. Kuzmichev, K. S. Pervakov, V. A. Vlasenko
Summary: We compare the structure of superconducting order parameter of overdoped BaFe1.88Ni0.12As2 and underdoped BaFe1.92Ni0.08As2 pnictides with similar T-c around 18.0-18.3 K. Using spectroscopy, we directly determine the magnitudes of the two microscopic superconducting order parameters and discuss their similarity, difference, and possible influence of antiferromagnetic phase on superconducting properties.
Article
Chemistry, Physical
Andrey V. Sadakov, Vladimir A. Vlasenko, Ivan A. Troyan, Oleg A. Sobolevskiy, Dmitrii V. Semenok, Di Zhou, Vladimir M. Pudalov
Summary: A comprehensive study was conducted on vortex phases and dynamics in the high-temperature superconductor YH(6) under a pressure of 200 GPa. The thermal activation energy and its dependence on magnetic field were analyzed using the thermally activated flux flow (TAFF) theory. The vortex phase transition from vortex glass to vortex liquid was studied, and a vortex phase diagram was constructed for superhydrides for the first time. The high flux flow barriers and crossover fields make YH6 an outstanding superconductor compared to other materials.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Chemistry, Physical
Leonid Morgun, Svetoslav Kuzmichev, Igor Morozov, Alena Degtyarenko, Andrey Sadakov, Andrey Shilov, Ilya Zhuvagin, Yevgeny Rakhmanov, Tatiana Kuzmicheva
Summary: A comprehensive study of the superconducting properties of underdoped NaFe0.979Co0.021As single crystals is presented, using a combination of upper critical field measurements and incoherent multiple Andreev reflection effect (IMARE) spectroscopy. The study reveals the temperature dependence of the Hc2(T) and the characteristics of the superconducting order parameters.
Article
Multidisciplinary Sciences
Vladimir D. Zvorykin, Natalia G. Borisenko, Kirill S. Pervakov, Alexey V. Shutov, Nikolay N. Ustinovskii
Summary: The hydrodynamics of plasma formed by the interaction of UV KrF laser pulses with foam targets was studied. The results showed that radiation propagated through foam targets at a speed of 80 km/s, while plasma stream velocities from both sides of the target were approximately the same, around 75 km/s, confirming the volumetric absorption of radiation and the explosive nature of plasma formation and expansion.
Article
Chemistry, Multidisciplinary
Ivan A. Troyan, Dmitrii V. Semenok, Anna G. Ivanova, Andrey V. Sadakov, Di Zhou, Alexander G. Kvashnin, Ivan A. Kruglov, Oleg A. Sobolevskiy, Marianna V. Lyubutina, Dmitry S. Perekalin, Toni Helm, Stanley W. Tozer, Maxim Bykov, Alexander F. Goncharov, Vladimir M. Pudalov, Igor S. Lyubutin
Summary: The chemical interaction of Sn with H-2 was studied using X-ray diffraction methods, revealing the superconducting properties and structure of SnH4 tetrahydride, as well as several lower hydrides. SnH4 showed unusual behavior in strong magnetic fields and its electrical resistance temperature dependence did not follow conventional theories. These findings suggest that superhydrides are more similar to cuprates than previously believed.
Article
Chemistry, Physical
A. A. Gippius, A. V. Gunbin, A. V. Tkachev, S. V. Zhurenko, D. I. Fazlizhanova, S. A. Kuzmichev, T. E. Kuzmicheva, V. Yu Verchenko, A. V. Shevelkov
Summary: A comprehensive study of the intermetallic superconductor Mo8Ga41 reveals the presence of an inherent surface superconducting phase in addition to the bulk superconducting phase. The s-wave type single-gap superconducting behavior with enhanced electron-phonon coupling is observed in the bulk phase. The surface phase shows a lower superconducting gap value, indicating a weak-coupling BCS limit. These findings help explain the multi-gap behavior in Mo8Ga41.
