Finite-Momentum Pairing State in Unconventional Rashba Systems

Kavli Affiliate: Ran Wang

| First 5 Authors: Ran Wang, Song-Bo Zhang, Ning Hao, ,

| Summary:

In systems with unconventional Rashba bands, we propose that a
finite-momentum pairing state can emerge without the need for an external
magnetic field. We analyze the phase transition from a zero-momentum
Bardeen-Cooper-Schrieffer (BCS) state to a finite-momentum pairing state using
a microscopic interaction model. We demonstrate that the coexistence of
zero-momentum and Larkin-Ovchinnikov (LO)-type pairings in different channels
provides a well understanding of recent experimental observations of
pair-density-wave (PDW) states. Furthermore, we propose that an s-wave BCS
superconductor-unconventional Rashba metal (SC-URM) junction can generate an
LO-type pairing state via an orbital-selective proximity effect. This
nontrivial state can be detected by measuring the Josephson current in an
SC-URM-SC junction or through Josephson scanning tunneling
microscopy/spectrosscopy (JSTM/S). Our results reveal that the internal
multi-orbital degrees of freedom play a crucial role in facilitating
finite-momentum pairing states.

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