Proximity-induced mixed odd-and even-frequency pairing in monolayer NbSe2

Article

关键词: TRANSITION-METAL DICHALCOGENIDES;    SUPERCONDUCTOR-FERROMAGNET STRUCTURES;    ISING SUPERCONDUCTIVITY;    GATED MOS2;    LAYER;   

DOI  :  10.1103/PhysRevB.97.224503

来源: SCIE

【 摘 要 】

Monolayer superconducting transition-metal dichalcogenide NbSe2 is a candidate for a nodal topological superconductor by magnetic field. Because of the so-called Ising spin-orbit coupling that strongly pins the electron spins to the out-of-plane direction, Cooper pairs in monolayer superconductor NbSe2 are protected against an applied in-plane magnetic field much larger than the Pauli limit. In monolayer NbSe2, in addition to the Fermi pockets at the corners of Brillouin zone with opposite crystal momentum similar to other semiconducting transition-metal dichalcogenids, there is an extra Fermi pocket around the Gamma point with much smaller spin splitting, which could lead to an alternative strategy for pairing possibilities that are manipulable by a smaller magnetic field. By considering a monolayer NbSe2-ferromagnet substrate junction, we explore the modified pairing correlations on the pocket at Gamma point in hole-doped monolayer NbSe2. The underlying physics is fascinating as there is a delicate interplay of the induced exchange field and the Ising spin-orbit coupling. We realize amixed singlet-triplet superconductivity, s + f, due to the Ising spin-orbit coupling. Moreover, our results reveal the admixture state including both odd-and even-frequency components, associated with the ferromagnetic proximity effect. Different frequency symmetries of the induced pairing correlations can be realized by manipulating the magnitude and direction of the induced magnetization.

【 授权许可】

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