Eur. Phys. J. B (2022) 95: 101
https://doi.org/10.1140/epjb/s10051-022-00369-y

Regular Article - Solid State and Materials

Topological defect states and phase transitions in mesoscopic superconducting squares with Rashba spin–orbit interaction

Department of Physics and Shanghai Key Laboratory of High Temperature Superconductors, Shanghai University, 200444, Shanghai, China

^b zgq_1981@shu.edu.cn

Received: 8 May 2022
Accepted: 18 June 2022
Published online: 28 June 2022

Abstract

Based on the spin-generalized Bogoliubov–de Gennes theory, we investigate the topological defect configurations in a mesoscopic superconducting square with spin–orbit (SO) interaction. The mixed even-parity d-wave and extended s-wave components can be obtained by suitable choice of the chemical potential in such a system. We find that several novel types of topological defect states can be generated in the presence of Rashba SO coupling when the external magnetic flux turns on. Unclosed domain-wall states carrying even or odd number of one-component vortices as well as double-quanta skyrmionic patterns can appear for different Rashba SO-coupling strengths. The next-nearest-neighbor hopping effect on the evolution of topological structures is further examined. A skyrmionic chain feature with one-component vortex–antivortex pairs can show up in the present mixed-pairing system. Our investigation may provide useful information for future experiments and shed new light on device designing.