We demonstrate that superconducting aluminium nano-bridges can be driven into a state with complete suppression of the critical supercurrent via electrostatic gating. Probing both in- and out-of-plane magnetic field responses in the presence of electrostatic gating can unveil the mechanisms that primarily cause the superconducting electric field effects. Remarkably, we find that a magnetic field, independently of its orientation, has only a weak influence on the critical electric field that identifies the transition from the superconducting state to a phase with vanishing critical supercurrent. This observation points to the absence of a direct coupling between the electric field and the amplitude of the superconducting order parameter or $2π$-phase slips via vortex generation. The magnetic field effect observed in the presence of electrostatic gating is described within a microscopic model where a spatially uniform inter-band $π$-phase is stabilized by the electric field. Such an intrinsic superconducting phase rearrangement can account for the suppression of the supercurrent, as well as for the weak dependence of the critical magnetic fields on the electric field.
Motivated by the recent experiments that reported the discovery of vortex Majorana bound states (vMBSs) in iron-based superconductors, we establish a portable scheme to unveil the non-Abelian statistics of vMBSs using normal fermionic modes. The unique non-Abelian statistics of vMBSs is characterized by the charge flip signal of the fermions that can be easily read out through the charge sensing measurement. In particular, the charge flip signal will be significantly suppressed for strong hybridized vMBSs or trivial vortex modes, which efficiently identifies genuine vMBSs. To eliminate the err…
Unveiling In-Gap States and Majorana Zero Modes in Superconductor-Topological Insulator Bilayer model
Materials Science and Technology Division, Oak Ridge National Laboratory（橡树岭国家实验室材料科学与技术分部）；Institute of Physics, Polish Academy of Sciences（波兰科学院物理研究所）；Microsoft Quantum, Station Q, University of California, Santa Barbara（微软量子、Station Q、加州大学圣塔芭芭拉分校）；Department of Physics and Astronomy, Purdue University（普渡大学物理与天文系）
Order-disorder transitions between glassy phases are quite common in nature and yet a comprehensive survey of the microscopic structural changes remains elusive since the scale of the constituents is tiny and in most cases few of them take part in the transformation. Vortex matter in type-II superconductors is a model system where some of the experimental challenges inherent to this general question can be tackled by adequately choosing the host superconducting sample. For instance, Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8 + δ}$ is a type-II superconductor with weak point disorder that presents a trans…
We study the unconventional superconducting correlations caused by a single isolated magnetic impurity in a conventional s-wave superconductor. Due to the local breaking of time-reversal symmetry, the impurity induces unconventional superconductivity which is even in both space and spin variables but odd under time inversion. We derive an exact proportionality relation between the even-frequency component of the local electron density of states and the imaginary part of the odd-frequency local pairing function. By applying this relation to scanning tunneling microscopy spectra taken on top of …
Bismuthates were the first family of oxide high-temperature superconductors, exhibiting superconducting transition temperatures (Tc) up to 32K, but the superconducting mechanism remains under debate despite more than 30 years of extensive research. Our angle-resolved photoemission spectroscopy studies on Ba$_{0.51}$K$_{0.49}$BiO$_3$ reveal an unexpectedly 34% larger bandwidth than in conventional density functional theory calculations. This can be reproduced by calculations that fully account for long-range Coulomb interactions --- the first direct demonstration of bandwidth expansion due to t…
Unveiling the superconducting scenario in multiphase superconductor CeRh$_2$As$_2$ from space-group symmetry analysis and DFT calculations
Saint Petersburg State University（圣彼得堡国立大学）；Kurnakov Institute of General and Inorganic Chemistry of RAS（俄罗斯科学院库尔纳科夫普通和无机化学研究所）；Institute of Strength Physics and Materials Science of RAS（俄罗斯科学院强度物理与材料科学研究所）；Donostia International Physics Center（多诺斯蒂亚国际物理中心）
Unveiling the nature of collective charge excitations in a cuprate superconductor
The Chinese University of Hong Kong（香港中文大学）；Universität Zürich（苏黎世大学）；Diamond Light Source（钻石光源）；Korea Advanced Institute of Science and Technology（韩国科学技术院）；KTH Royal Institute of Technology（瑞典皇家理工学院）；The University of Tokyo（东京大学）；Max Planck Institute for Solid State Research（马克斯·普朗克固体研究所）；Institut Néel, CNRS and Université Grenoble Alpes（内尔研究所，法国国家科学研究中心与格勒诺布尔阿尔卑斯大学）
The nematic order (nematicity) is considered one of the essential ingredients to understand the mechanism of Fe-based superconductivity. In most Fe-based superconductors (pnictides), nematic order is reasonably close to the antiferromagnetic order. In FeSe, in contrast, a nematic order emerges below the structure phase transition at T_s = 90 K with no magnetic order. The case of FeSe is of paramount importance to a universal picture of Fe-based superconductors. The polarized ultrafast spectroscopy provides a tool to probe simultaneously the electronic structure and the magnetic interactions th…
In our desire to give a new suggestion for H-based superconductors experiments we present a theoretical framework for understanding the impact of an applied electric field on pressured hydride superconductors. We study a material at pressure $p$, when it possesses insulator-superconductor transition, at the respective superconducting critical temperature $T_{cr}$. The theory shows the applied electric field penetrates the material and forces the Cooper pairs to Bose condensate. If one applies an electric field and then increases the temperature, the theory predicts novel critical temperature $…
We use the formerly derived explicit analytical expressions for the conductivity of nanostructured superconductors supercooled below the critical temperature in electric field. Computer simulations reveal that the negative differential conductivity region of the current-voltage characteristic leads to excitation of electric oscillations. We simulate a circuit with distributed elements as a first step to obtain gigahertz oscillations. This gives a hint that a hybrid device of nanostructured superconductors will work in terahertz frequencies. If the projected setup is successful, we consider the…
We formulate a theory based on the time-dependent Ginzburg Landau (TDGL) theory and Newtonian vortex dynamics to study the transverse acousto-electric response of a type-II superconductor with Abrikosov vortex lattice. When exposed to a transverse acoustic wave, Cooper pairs emerge from the the moving atomic lattice and moving electrons. As in the Tolman-Stewart effect in a normal metal, an electromagnetic field is radiated from the superconductor. We adapt the equilibrium-based TDGL theory to this non-equilibrium system by using a floating condensation kernel. Due to the interaction between n…
Theory of the influence of the thermal fluctuations on the electric transport beyond linear response in superconductors is developed within the framework of the time dependent Ginzburg - Landau approach. The I - V curve is calculated using the dynamical self - consistent gaussian approximation. Under certain conditions it exhibits a reentrant behaviour acquiring an S - shape form. The unstable region below a critical temperature $T^{\ast }$ is determined for arbitrary dimensionality ($D=1,2,3$) of the thermal fluctuations. The results are applied to analyse the transport data on nanowires and …
We predict a new effect in condensed matter surface magnetization of the vortex phase of a superconductor induced by electric field. The magnetized superconductor should be one of the plates of a plane capacitor on which a voltage has to be applied. Applying alternating voltage to the capacitor, electrostatic induction leads to oscillations of the magnetic moment which has to be measured by electromotive force inducted in a detector coil. The derived explicit formula for the magnetization contains the effective mass of Cooper pairs and a systematic investigation of the predicted magnetization …
In the strong coupling Bose-Einstein Condensation (BEC) regime the superconductors have two characteristic temperatures: $T^*$- onset of fermion pairing and $T_{sc}$- onset of superconductivity, such that $T_{sc}<T^*$. In the present article, we consider time dependent Ginzburg-Landau theory of superconductors with slab geometry and show that applied electric field, in the temperature interval $(T_{sc},T^*)$, Bose condenses the Cooper pairs thereby increasing the superconductor critical temperature $T^E_{sc}>T_{sc}$. Important consequence is the fact that arbitrary temperature within the inter…
A short review of the history and the contemporary numerical calculations of the operation of an electronic device for generation of electric oscillations by negative differential conductivity of a supercooled below the critical temperature superconductor. The superconductor is cooled below the critical temperature at applied small constant electric field, which keeps the superconductor in normal state. To simulate the device operation, beforehand analytical expressions for the conductivity of nano-structured superconductors supercooled below the critical temperature in electric field are used…
Electrical conductivity beyond linear response in layered superconductors under magnetic field
利用含时Ginzburg-Landau方法研究了强II型超导体的非线性响应。耗散以通量流的形式存在，定量地研究了线性响应之外的通量流。热波动，由朗之万白噪声表示，被认为是足够强大的融化的Abrikosov涡晶格所创建的磁场到一个移动的涡旋液体和边缘化的不均匀性的涡旋钉扎的影响。超导体的层状结构是由劳伦斯-多尼亚克模型。在高斯近似下处理动力学中的非线性相互作用项，从而超越了通常使用的最低朗道能级近似，处理任意磁场。计算了任意温度下的I-V曲线，并与高$T_{c}$超导体$_{2}$ $_{3}$ O $%_{7-δ}$的实验数据进行了比较。
We investigate inverse proximity effects in a spin-triplet superconductor (TSC) interfaced with a ferromagnet (FM), assuming different types of magnetic profiles and chiral or helical pairings. The region of the coexistence of spin-triplet superconductivity and magnetism is significantly influenced by the orientation and spatial extension of the magnetization with respect to the spin configuration of the Cooper pairs, resulting into clearcut anisotropy signatures. A characteristic mark of the inverse proximity effect arises in the induced spin-polarization at the TSC interface. This is unexpec…
Dynamic states offer extended possibilities to control the properties of quantum matter. Recent efforts are focused on studying the ordered states which appear exclusively under the time-dependent drives. Here we demonstrate a class of systems which feature dynamic spin-triplet superconducting order stimulated by the alternating electric field. The effect is based on the interplay of ferromagnetism, interfacial spin-orbital coupling (SOC) and the condensate motion driven by the field, which converts hidden static p-wave order, produced by the joint action of the ferromagnetism and the SOC, int…
We studied the effects of multiband electronic structure on the thermoelectric and electrical transport properties in the normal state of kagome superconductors $A$V$_3$Sb$_5$ ($A$ = K, Rb, Cs). In all three members, the multiband nature is manifested by sign changes in the temperature dependence of the Seebeck and Hall resistivity, together with sublinear response of the isothermal Nernst and Hall effects to external magnetic fields in the charge ordered state. Moreover, ambipolar transport effects appear ubiquitously in all three systems, giving rise to sizable Nernst signal. Finally, possib…
We report the numerical solutions of the system of equations, which describes the electrodynamics of s-wave superconductors, for time independent fields and half-plane superconductor geometry. The results are: i)the applied magnetic field increases the Ginzburg-Landau (GL) coherence length and suppresses the superconductivity, ii)the applied electric field decreases GL coherence length and supports the superconductivity, iii) if the applied magnetic field is fixed and the applied electric field increases the London penetration depth of the magnetic field decreases. The main conclusion is that …
Structural and electrical transport properties of superconducting Au{0.7}In{0.3} films: A random array of superconductor-normal metal-superconductor (SNS) Josephson junctions
The structural and superconducting properties of Au{0.7}In{0.3} films, grown by interdiffusion of alternating Au and In layers, have been studied. The films were found to consist of a uniform solid solution of Au{0.9}In{0.1}, with excess In precipitated in the form of In-rich grains of various Au-In phases (with distinct atomic compositions), including intermetallic compounds. As the temperature was lowered, these individual grains became superconducting at a particular transition temperature (Tc), determined primarily by the atomic composition of the grain, before a fully superconducting stat…
Current-Induced Superconductor-Insulator Transition in Granular High-T_c Superconductors
在这项工作中，我们报告了一个系统的研究电流对颗粒Y $_{1-x}$ Pr $_{x}$ Ba $_{2}$ Cu $_{3}$ O $_{7-δ}$样品的超导性能的影响，x接近临界Pr浓度以上的超导性消失。结果表明，在外加电流的驱动下，超导体-绝缘体发生了量子相变（SIT），电流诱导的SIT可以看作是磁场调谐的SIT的动力学对应物.
We realize superconductor-insulator transitions (SIT) in mechanically exfoliated Bi$_2$Sr$_2$CaCu$_2$O$_{8+δ}$ (BSCCO) flakes and address simultaneously their transport properties as well as the evolution of density of states. Back-gating via the solid ion conductor engenders a reversible SIT in BSCCO, as lithium ions from the substrate are electrically driven into and out of BSCCO. Scaling analysis indicates that the SIT follows the theoretical description of a two-dimensional quantum phase transition (2D-QPT). We further carry out tunneling spectroscopy in graphite(G)/BSCCO heterojunctions. …
In this letter, we address the impact of the electric field on superconductors which are insulators in the normal state, superconducting semiconductors at low carrier concentration and ultracold gas of fermions in the strongly interacting regime. The electric field penetrates these systems and affects on the Cooper pairs. We show that if there are Cooper pairs above the superconductor critical temperature the electric field forces the Cooper pairs to Bose condensate and the onset of the superconductivity, thereby increasing the critical temperature. To study this phenomenon we numerically solv…
We present detailed neutron scattering studies of the static and dynamic stripes in an optimally doped high-temperature superconductor, La$_2$CuO$_{4+y}$. We find that the dynamic stripes do not disperse towards the static stripes in the limit of vanishing energy transfer. We conclude that the dynamic stripes observed in neutron scattering experiments are not the Goldstone modes associated with the broken symmetry of the simultaneously observed static stripes, but rather that the signals originate from different domains in the sample. These domains may be related by structural twinning, or may…
