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
Physics, Multidisciplinary
Hai Li, Xiang Hu, Gang Ouyang
Summary: In this study, we theoretically investigate the transport properties in normal-superconducting junctions based on semi-Dirac materials (SDMs) using the framework of Bogoliubov-de Gennes equation. Due to the intrinsic anisotropy of SDMs, the configuration of Andreev reflection (AR) and the differential conductance strongly depend on the orientation. The results show that for transport along the linear dispersion direction, there is a clear crossover from retro AR to specular AR with increasing bias-voltage, and the differential conductance oscillates without decaying with the interfacial barrier strength. Conversely, for transport along the quadratic dispersion direction, the boundary between retro AR and specular AR becomes ambiguous as the orientation angle increases, and the differential conductance decays with increasing momentum mismatch or interfacial barrier strength. The pseudo-spin textures are used to illustrate the underlying physics behind the anisotropic coherent transport properties.
NEW JOURNAL OF PHYSICS
(2022)
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
Chemistry, Multidisciplinary
Wonhee Ko, Sang Yong Song, Jiaqiang Yan, Jose L. Lado, Petro Maksymovych
Summary: This study introduces the unique capability of tunneling Andreev reflection (TAR) to probe unconventional pairing symmetry in low-dimensional unconventional superconductors. By studying the paradigmatic FeSe superconductor, we provide direct evidence of sign-changing order parameter, reveal the existence of two superconducting gaps, and confirm the local suppression of superconductivity along the nematic twin boundary. These findings enable new atomic-scale insight into microscopic, inhomogeneous, and interfacial properties of emerging quantum materials.
Article
Physics, Condensed Matter
Hong Li, Xinjian Yang
Summary: The tunneling conductance and shot noise in topological insulator-based ferromagnet/ dx2_y2 + idxy mixed wave superconductor (TI-based FM/ dx2_y2 + idxy SC) junctions are calculated using the Dirac-Bogoliubov-de Gennes equation and Blonder-Tinkham-Klapwijk theory. The analysis of conductance and shot noise reveals the dependence of Andreev reflection on factors such as magnetic gap m, gate potential U, and the ratio of pair potential between dx2_y2 and dxy components. The study also suggests that the turning point at m = EF can be utilized as a criterion for distinguishing between specular Andreev reflection and Andreev retro-reflection in thin film TI-based FM/ dx2_y2 + idxy SC structures, and the pairing symmetry and magnetic gap can be determined through scanning tunnel spectroscopy experiments.
SOLID STATE COMMUNICATIONS
(2023)
Article
Physics, Applied
Sedighe Salimian, Matteo Carrega, Isha Verma, Valentina Zannier, Michal P. Nowak, Fabio Beltram, Lucia Sorba, Stefan Heun
Summary: High-quality InSb nanoflags, as a versatile III-V semiconductor material, show great potential in advanced quantum technologies, especially in realizing topological superconducting states. Fabrication of ballistic Josephson-junction devices based on InSb nanoflags allows for tunable proximity-induced supercurrent, indicating a promising platform for future quantum applications.
APPLIED PHYSICS LETTERS
(2021)
Article
Materials Science, Multidisciplinary
S. J. Carreira, D. Sanchez-Manzano, M. -W. Yoo, K. Seurre, V. Rouco, A. Sander, J. Santamaria, A. Anane, J. E. Villegas
Summary: In this study, spin-pumping effects in bilayers of a soft metallic ferromagnet and high-temperature superconductor YBCO were investigated using wideband ferromagnetic resonance. The Gilbert damping in the ferromagnet dropped drastically across the normal-superconducting transition, with different behaviors observed depending on the interface morphology. The unique behavior was attributed to the quasiparticle density of states at the YBCO surface and the zero-gap nodes in the momentum space.
Article
Physics, Multidisciplinary
Morteza Salehi
Summary: We demonstrate that a ferromagnetic/superconductor junction on the surface of 3D TIs exhibits an anisotropic angle-dependent Andreev reflection when the in-plane magnetization is perpendicular to the junction. The movement of the Dirac cone and the induced gap result in the anisotropic reflection and the anomalous Hall conductance parallel to the interface. The existence of an indirect gap in the junction removes the transport signatures of Majorana bound states. A torque called Andreev Transfer Torque (ATT) is imposed on the junction due to the full spin-momentum locking of Dirac fermions on the surface of 3DTIs, and we propose an experimental setup to detect it.
Article
Physics, Multidisciplinary
Hamidreza Emamipour
Summary: This study investigates the tunneling conductance in graphene-based ferromagnet-normal metal-superconductor junction with time-reversal symmetry broken. It is found that exchange field of ferromagnet suppresses the tunneling conductance for various pairing states, but increases when Fermi wave mismatch is present. Adjusting bias voltages and junction parameters can help differentiate between different symmetry states.
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
Materials Science, Multidisciplinary
Yuhi Takabatake, Shu-Ichiro Suzuki, Yukio Tanaka
Summary: In this study, the tunneling conductance of the (d+ip)-wave superconductor on the (110) surface of a high-Tc cuprate superconductor is theoretically investigated. The results show that the zero-bias peak of the d-wave superconductor is robust against the spin-triplet p-wave surface subdominant order. Comparing numerical and experimental results indicates the feasibility of spin-triplet p-wave surface subdominant order.
Article
Materials Science, Multidisciplinary
K. Borisov, J. Ehrler, C. Fowley, B. Eggert, H. Wende, S. Cornelius, K. Potzger, J. Lindner, J. Fassbender, R. Bali, P. Stamenov
Summary: The spin polarization of B2-ordered Fe60Al40 thin films increases monotonically with ion fluence, reaching a relatively high polarization of 46% on 40 nm films irradiated with 2 x 10(16) ions/cm(2) at 30 keV. An interesting divergence in trends between magnetization and SHA is observed for low disorder concentrations. The high spin polarization and its broad tunability range make ion-irradiated Fe60Al40 a promising material for spin electronic devices.
Article
Materials Science, Multidisciplinary
Guangrui Zhang, Hongbo Hao, Yuping Liang, Yu Qiao, Songwei Bai, Heyan Liu, Hongzhi Luo
Summary: The atomic ordering, electronic structure, magnetic properties and martensitic transformation of three new all-dmetal Heusler alloys Mn2PtZ (Z = Sc, Ti and V) have been investigated theoretically to discover new magnetic shape memory alloys (MSMAs). Depending on the different third transition metal element Z, Mn2PtSc and Mn2PtTi tend to form XA structure while Mn2PtV forms L21 structure. Mn2PtTi is a possible new MSMA with a high martensitic transformation temperature and a large energy difference between the martensite and austenite, making it a promising candidate for MSMAs with wide applications.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2023)
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
Physics, Applied
Sake Wang, Nguyen T. Hung, Hongyu Tian, Md Shafiqul Islam, Riichiro Saito
Summary: The proposed device can operate at room temperature, with the advantage of low-voltage operation and high response speed. Additionally, the model has potential applications in room-temperature nanoelectronics.
PHYSICAL REVIEW APPLIED
(2021)
