Spinpolarized superconductivity: Order parameter topology, current dissipation, and multipleperiod Josephson effect
Abstract
We discuss transport properties of fully spinpolarized triplet superconductors, where only electrons of one spin component (along a certain axis) are paired. Due to the structure of the order parameter space, wherein phase and spin rotations are intertwined, a configuration where the superconducting phase winds by 4 π in space is topologically equivalent to a configuration with no phase winding. This opens the possibility of supercurrent relaxation by a smooth deformation of the order parameter, where the order parameter remains nonzero at any point in space throughout the entire process. During the process, a spin texture is formed. We discuss the conditions for such processes to occur and their physical consequences. In particular, we show that when a voltage is applied, they lead to an unusual alternatingcurrent Josephson effect whose period is an integer multiple of the usual Josephson period. These conclusions are substantiated in a simple timedependent GinzburgLandau model for the dynamics of the order parameter. One of the potential applications of our analysis is for moiré systems, such as twisted bilayer and double bilayer graphene, where superconductivity is found in the vicinity of ferromagnetism.
 Publication:

Physical Review Research
 Pub Date:
 January 2021
 DOI:
 10.1103/PhysRevResearch.3.013051
 arXiv:
 arXiv:2006.10073
 Bibcode:
 2021PhRvR...3a3051C
 Keywords:

 Condensed Matter  Superconductivity;
 Condensed Matter  Strongly Correlated Electrons
 EPrint:
 12+7 pages, 6 figures