paper

Lifshitz transitions and Weyl semimetals from a topological superconductor with supercurrent flow

arXiv:2404.18131 · doi:10.1103/PhysRevResearch.6.033060

Abstract

A current flowing through a superconductor induces a spatial modulation in its superconducting order parameter, characterized by a wavevector related to the total momentum of a Cooper pair. Here we investigate this phenomenon in a -wave topological superconductor, described by a one-dimensional Kitaev model. We demonstrate that, by treating as an extra synthetic dimension, the current carrying non-equilibrium steady state can be mapped into the ground state of a half-filled two-dimensional Weyl semimetal, whose Fermi surface exhibits Lifshitz transitions when varying the model parameters. Specifically, the transition from Type-I to Type-II Weyl phases corresponds to the emergence of a gapless -wave superconductor, where Cooper pairs coexist with unpaired electrons and holes. Such transition is signaled by the appearance of a sharp cusp in the -dependence of the supercurrent, at a critical value that is robust to variations of the chemical potential . We determine the maximal current that the system can sustain in the topological phase, and discuss possible implementations.

20 pages, 10 figures

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