The B-phase of superfluid 3 He is a 3D time-reversal invariant (TRI) topological superfluid with an isotropic energy gap, ∆, separating the ground-state and bulk continuum states. We report calculations of surface spectrum, spin-and mass current densities originating from the Andreev surface states for confined 3 He-B. The surface states are Majorana Fermions with their spins polarized transverse to their direction of propagation along the surface, p . The negative energy states give rise to a ground-state helical spin current confined on the surface. The spectral functions reveal the subtle role of the spin-polarized surface states in relation to the ground-state spin current. By contrast, these states do not contribute to the T = 0 mass current. Superfluid flow through a channel of confined 3 He-B is characterized by the flow field, p s =h 2 ∇ϕ. The flow field breaks SO(2) L z +S z rotational symmetry and time reversal (T). However, the Bogoliubov-Nambu Hamiltonian remains invariant under the combined symmetry, U z (π) × T, where U z (π) is a π rotation about the surface normal. As a result the B-phase in the presence of a superflow remains a topological phase with a gapless spectrum of Majorana modes on the surface. Thermal excitation of the Doppler shifted Majorana branches leads to a power law suppression of the superfluid mass current for 0 < T 0.5T c , providing a direct signature of the Majorana branches of surface excitations in the fully gapped 3D topological superfluid, 3 He-B. Results are reported for the superfluid fraction (mass current) and helical spin current for confined 3 He-B, including the temperature dependences, as well as dependences on confinement, pressure and interactions between quasiparticles.

Electric-field control of magnetism in ferromagnetic/ferroelectric multiferroic heterostructures is a promising way to realize fast and nonvolatile random-access memory with high density and low-power consumption. An important issue that has not been solved is the magnetic responses to different types of ferroelectric-domain switching. Here, for the first time three types of magnetic responses are reported induced by different types of ferroelectric domain switching with in situ electric fields in the CoFeB mesoscopic discs grown on PMN-PT(001), including type I and type II attributed to 109°, 71°/180° ferroelectric domain switching, respectively, and type III attributed to a combined behavior of multiferroelectric domain switching. Rotation of the magnetic easy axis by 90° induced by 109° ferroelectric domain switching is also found. In addition, the unique variations of effective magnetic anisotropy field with electric field are explained by the different ferroelectric domain switching paths. The spatially resolved study of electric-field control of magnetism on the mesoscale not only enhances the understanding of the distinct magnetic responses to different ferroelectric domain switching and sheds light on the path of ferroelectric domain switching, but is also important for the realization of low-power consumption and high-speed magnetic random-access memory utilizing these materials.

Band engineering in layered metal dichalcogenides leads to a variety of physical phenomena and has obtained considerable attention recently. In this work, pressure‐induced metallization and superconductivity in pristine 1T‐SnSe2 is reported via electrical transport and synchrotron X‐ray diffraction experiments. Electrical transport results show that the metallization emerges above 15.2 GPa followed by appearance of superconducting transition at 18.6 GPa. The superconductivity is robust with a nearly constant Tc ≈ 6.1 K between 30.1 and 50.3 GPa. High‐pressure synchrotron X‐ray diffraction experiments indicate that the 1T‐SnSe2 phase maintains up to 46.0 GPa. Although the theoretical predicted structural transition and decomposition of SnSe2 into Sn3Se4 and Se are not detected, it is argued that the structural instability under high pressure might be crucial for the superconductivity. These findings demonstrate that 1T‐SnSe2 is a very rare system from which superconductivity can be driven via multiple ways.

Recent theories of Sr 2 RuO 4 based on the interplay of strong interactions, spin-orbit coupling and multi-band anisotropy predict chiral or helical ground states with strong anisotropy of the pairing states, with deep minima in the excitation gap, as well as strong phase anisotropy for the chiral ground state. We develop time-dependent mean field theory to calculate the Bosonic spectrum for the class of 2D chiral superconductors spanning 3 He-A to chiral superconductors with strong anisotropy. Chiral superconductors support a pair of massive Bosonic excitations of the time-reversed pairs labeled by their parity under charge conjugation. These modes are degenerate for 2D 3 He-A. Crystal field anisotropy lifts the degeneracy. Strong anisotropy also leads to low-lying Fermions, and thus to channels for the decay of the Bosonic modes. Selection rules and phase space considerations lead to large asymmetries in the lifetimes and hybridization of the Bosonic modes with the continuum of un-bound Fermion pairs. We also highlight results for the excitation of the Bosonic modes by microwave radiation that provide clear signatures of the Bosonic modes of an anisotropic chiral ground state.

In article number https://doi.org/10.1002/aelm.201800155, Kaiyou Wang, Zhaorong Yang, and co‐workers report a pressure‐induced superconducting layered metal dichalcogenide. High pressure represents a clean and effective strategy for achieving superconductivity in SnSe2 in addition to intercalation, gating, and few‐layer fabrication. The achieved superconductivity of 6.1 K will greatly promote future research in other metal dichalcogenides.

Asymmetric reversible diode-like resistive switching behaviors in ferroelectric BaTiO 3 3 3 thin films *Zhang Fei(张 飞) a) , Lin Yuan-Bin(林远彬) a) , Wu Hao(吴 昊) a) , Miao Qing(苗 青) a) , Gong Ji-Jun(巩纪军) a) , Chen Ji-Pei(陈继培) a) , Wu Su-Juan(吴素娟) a) , Zeng Min(曾 敏) a) , Gao Xing-Sen(高兴森) a) † , and Liu Jun-Ming(刘俊明) b) ‡

Inlet and outlet boundary conditions (BCs) play an important role in newly emerged image-based computational hemodynamics for blood flows in human arteries anatomically extracted from medical images. We developed physiological inlet and outlet BCs based on patients’ medical data and integrated them into the volumetric lattice Boltzmann method. The inlet BC is a pulsatile paraboloidal velocity profile, which fits the real arterial shape, constructed from the Doppler velocity waveform. The BC of each outlet is a pulsatile pressure calculated from the three-element Windkessel model, in which three physiological parameters are tuned by the corresponding Doppler velocity waveform. Both velocity and pressure BCs are introduced into the lattice Boltzmann equations through Guo’s non-equilibrium extrapolation scheme. Meanwhile, we performed uncertainty quantification for the impact of uncertainties on the computation results. An application study was conducted for six human aortorenal arterial systems. The computed pressure waveforms have good agreement with the medical measurement data. A systematic uncertainty quantification analysis demonstrates the reliability of the computed pressure with associated uncertainties in the Windkessel model. With the developed physiological BCs, the image-based computation hemodynamics is expected to provide a computation potential for the noninvasive evaluation of hemodynamic abnormalities in diseased human vessels.

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