Topological defects and phase transitions in small mesoscopic chiral p-wave superconductors

Date: 5 December 2017

Venue: University of Antwerp - Campus Groenenborger - Room U.244 - Groeneborgerlaan 171 - 2020 Antwerp

Time: 4:00 PM - 5:00 PM

Organization / co-organization: Condensed Matter Theory

Short description: Condensed Matter Theory seminar presented by Dr Linfeng Zhang

Chiral p-wave superconductivity exhibits topological order.  Under certain conditions, a chiral p-wave superconductor can support Majorana fermions and non-Abelian statistics, which can be used to build topological quantum computers. In this talk, I will first introduce the topological quantum computing and Majorana fermions.  Then, I will present our recent results on topological defect states in mesoscopic chiral p-wave superconductors. 

By solving the microscopic Bogoliubov-de Gennes equations self-consistently, we obtained the equilibrium phase diagram for small mesoscopic disks in the presence of magnetic field.  In the ultra-small limit, the cylindrically symmetric giant-vortex states are the ground state of the system. However, with increasing sample size, the cylindrical symmetry is broken as the two components of the order parameter segregate into domains, and the number of fragmented domain walls between them characterizes the resulting states.

Such domain walls are topological defects unique for the p-wave order, and constitute a dominant phase in the mesoscopic regime. Moreover, we find two possible types of domain walls, identified by their chirality-dependent interaction with the edge states.

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