Absence of Hall effect due to Berry curvature in phase space.

Transverse current due to Berry curvature in phase space is formulated based on the Boltzmann equations with the semiclassical equations of motion for an electron wave packet. It is shown that the Hall effect due to the phase space Berry curvature is absent because the contributions from "anomalous velocity" and "effective Lorentz force" are completely cancelled out.

Orbital Edelstein Effect as a Condensed-Matter Analog of Solenoids.

We theoretically study current-induced orbital magnetization in a chiral crystal. This phenomenon is an orbital version of the Edelstein effect. We propose an analogy between the current-induced orbital magnetization and an Ampère field in a solenoid in classical electrodynamics. To quantify this effect, we define a dimensionless parameter from the response coefficients relating a current density with an orbital magnetization. This dimensionless parameter can be regarded as a number of turns within a unit cell when the crystal is regarded as a solenoid, and it represents how "chiral" the crystal is. By focusing on the dimensionless parameter, one can design a band structure that realizes the induction of large orbital magnetization. In particular, a Weyl semimetal with all of the Weyl nodes close to the Fermi energy can have a large value for this dimensionless parameter, which can exceed that of a classical solenoid.

[Suspended Ventricular Septal Defect Closure Due to Heparin Resistance;Report of a Case].

We present a case of heparin resistance whereby open heart surgery was discontinued. A 53-year-old woman who was diagnosed with ventricular septal defect and atrial septal defect was scheduled for intracardiac repair. However, after intravenous heparin (400 U kg-1) supplementation, the activated clotting time (ACT) increased only to seconds. The operation was discontinued because the addition of heparin( 200 U kg-1) did not show sufficient prolongation of ACT, fully indicative of heparin resistance. Additional antithrombin III concentrate was also ineffective. Postoperative study of the administration of heparin in vitro to the patient's serum showed the probability of transient heparin resistance arising from the stress of surgery.

Anisotropic Paramagnetic Meissner Effect by Spin-Orbit Coupling.

Conventional s-wave superconductors repel an external magnetic field. However, a recent experiment [A. Di Bernardo et al., Phys. Rev. X 5, 041021 (2015)] has tailored the electromagnetic response of superconducting correlations via adjacent magnetic materials. We consider another route of altering the Meissner effect where spin-orbit interactions induce an anisotropic Meissner response that changes sign depending on the field orientation. The tunable electromagnetic response opens new paths in the utilization of hybrid systems comprising magnets and superconductors.

Current-induced Orbital and Spin Magnetizations in Crystals with Helical Structure.

We theoretically show that in a crystal with a helical lattice structure, orbital and spin magnetizations along a helical axis are induced by an electric current along the helical axis. We propose a simple tight-binding model for calculations, and the results can be generalized to any helical crystals. The induced magnetizations are opposite for right-handed and left-handed helices. The current-induced spin magnetization along the helical axis comes from a radial spin texture on the Fermi surface. This is in sharp contrast to Rashba systems where the induced spin magnetization is perpendicular to the applied current.

Spin current in generic hybrid structures due to interfacial spin-orbit scattering.

We demonstrate a general principle that hybrid structures of any sort inevitably will give rise to a pure spin current flowing parallel to the interface region when a charge current is injected. This stems from the broken mirror symmetry near the interface which gives rise to spin-orbit coupling that deflects incoming electrons in a spin-discriminating fashion. We establish a general analytical condition for the appearance of this effect, and calculate the transverse spin current explicitly using two different models. In addition, we investigate how the process of Andreev reflection influences this phenomenon in the scenario where one of the materials is superconducting.

Anomalous Meissner effect in a normal-metal-superconductor junction with a spin-active interface.

We investigate Meissner effect in normal-metal-superconductor junctions where the interface is spin active. We find that orbital magnetic susceptibility of the normal metal shows highly nontrivial behavior. In particular, the magnetic susceptibility depends on the temperature in an oscillatory fashion, accompanied by its sign change. Correspondingly, the magnetic field and current density can spatially oscillate in the normal metal. These results are attributed to the generation of odd-frequency pairing due to the spin-active interface.

Transport properties in ferromagnetic Josephson junctions between triplet superconductors.

Charge and spin Josephson currents in a ballistic superconductor-ferromagnet-superconductor junction with spin-triplet pairing symmetry are studied using the quasiclassical Eilenberger equation. The gap vector of superconductors has an arbitrary relative angle with respect to magnetization of the ferromagnetic layer. We clarify the effects of the thickness of the ferromagnetic layer and the magnitude of the magnetization on the Josephson charge and spin currents. We find that the 0-π transition can occur when the misorientation angle between the exchange field of the ferromagnetic layer and the d-vector is smaller than π/4. We also show how spin current flows due to misorientation between the exchange field and the d-vector.

Gate-controlled one-dimensional channel on the surface of a 3D topological insulator.

We investigate the formation of one-dimensional channels on the topological surface under the gate electrode. The energy dispersion of these channels is almost linear in momentum, and its velocity and sign are sensitively dependent on the strength of the gate voltage. Consequently, the local density of states near the gated region has an asymmetric structure with respect to zero energy. In the presence of the electron-electron interaction, the correlation effect can be tuned by the gate voltage. We also suggest a tunneling experiment to verify the presence of these bound states.

Anomalous Andreev bound state in noncentrosymmetric superconductors.

We study edge states of noncentrosymmetric superconductors where spin-singlet d-wave pairing mixes with spin-triplet p (or f)-wave one by spin-orbit coupling. For d(xy)-wave pairing, the obtained Andreev bound state has an anomalous dispersion as compared to conventional helical edge modes. A unique topologically protected time-reversal invariant Majorana bound state appears at the edge. The charge conductance in the noncentrosymmetric superconductor junctions reflects the anomalous structures of the dispersions, particularly the time-reversal invariant Majorana bound state is manifested as a zero bias conductance peak.

Unconventional superconductivity on a topological insulator.

We study proximity-induced superconductivity on the surface of a topological insulator (TI), focusing on unconventional pairing. We find that the excitation spectrum becomes gapless for any spin-triplet pairing, such that both subgap bound states and Andreev reflection is strongly suppressed. For spin-singlet pairing, the zero-energy surface state in the d(xy)-wave case becomes a Majorana fermion, in contrast with the situation realized in the topologically trivial high-T(c) cuprates. We also study the influence of a Zeeman field on the surface states. Both the magnitude and direction of this field are shown to strongly influence the transport properties, in contrast with the case without TI. We predict an experimental signature of the Majorana states via conductance spectroscopy.

Manipulation of the Majorana fermion, Andreev reflection, and Josephson current on topological insulators.

We study theoretically the transport properties of a normal metal (N)/ferromagnet insulator (FI)/superconductor (S) junction and a S/FI/S junction formed on the surface of a three-dimensional topological insulator, where the chiral Majorana mode exists at the FI/S interface. We find the chiral Majorana mode generated in N/FI/S and S/FI/S junctions is very sensitively controlled by the direction of the magnetization m in the FI region. In particular, the current-phase relation of the Josephson current in S/FI/S junctions has a phase shift of neither 0 nor pi that can be tuned continuously by the component of m perpendicular to the interface.

Giant spin rotation in the junction between a normal metal and a quantum spin Hall system.

We study theoretically the reflection problem in the junction between a normal metal and an insulator characterized by a parameter M, which is a usual insulator for M>0 or a quantum-spin-Hall system for M<0. The spin rotation angle alpha at the reflection is obtained as a function of M and the incident angle theta measured from the normal to the interface. The alpha shows rich structures around the quantum critical point M=0 and theta=0; i.e., alpha can be as large as approximately pi at an incident angle in the quantum spin Hall case M<0 because the helical edge modes resonantly enhance the spin rotation, which can be used to map the energy dispersion of the helical edge modes. As an experimentally relevant system, we also study the spin rotation effect in quantum-spin-Hall-normal-metal-quantum-spin-Hall trilayer junction.

Pairing symmetry conversion by spin-active interfaces in magnetic normal-metal-superconductor junctions.

We study the proximity-induced superconducting correlations in a normal metal connected to a superconductor when the interface between them is spin active and the normal metal is ballistic or diffusive. Remarkably, for any interface spin polarization there is a critical interface resistance, above which the conventional even-frequency proximity component vanishes completely at the chemical potential, while the odd-frequency component remains finite. We propose a way to unambiguously observe the odd-frequency component.

Strong parity mixing in the Fulde-Ferrell-Larkin-Ovchinnikov superconductivity in systems with coexisting spin and charge fluctuations.

We study the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state of spin fluctuation mediated pairing, and focus on the effect of coexisting charge fluctuations. We find that (i) consecutive transitions from singlet pairing to FFLO and further to S_{z}=1 triplet pairing can generally take place upon increasing the magnetic field when strong charge fluctuations coexist with spin fluctuations, and (ii) the enhancement of the charge fluctuations lead to a significant increase of the parity mixing in the FFLO state, where the triplet/singlet component ratio in the gap function can be close to unity. We propose that such consecutive pairing state transition and strong parity mixing in the FFLO state may take place in a quasi-one-dimensional organic superconductor (TMTSF)2X.

Chirality sensitive effect on surface states in chiral p-wave superconductors.

We study the local density of states at the surface of a chiral p-wave superconductor in the presence of a weak magnetic field. As a result, the formation of low-energy Andreev bound states is either suppressed or enhanced by an applied magnetic field, depending on its orientation with respect to the chirality of the p-wave superconductor. Similarly, an Abrikosov vortex, which is situated not too far from the surface, leads to a zero-energy peak of the density of states, if its chirality is the same as that of the superconductor, and to a gap structure for the opposite case. We explain the underlying principle of this effect and propose a chirality sensitive test on unconventional superconductors.

Supercurrent switch in graphene pi junctions.

We study the supercurrent in a superconductor/ferromagnet/superconductor graphene junction. In contrast to its metallic counterpart, the oscillating critical current in our setup decays only weakly upon increasing the exchange field and junction width. We find an unusually large residual value of the supercurrent at the oscillatory cusps due to a strong deviation from a sinusoidal current-phase relationship. Our findings suggest a very efficient device for dissipationless supercurrent switching.