Ground-state angular momentum, spectral asymmetry, and topology in chiral superfluids and superconductors

• Published in: Physical Review B
• Main Author: Ojanen, Teemu
• Other Authors: Department of Applied Physics, Aalto-yliopisto, Aalto University
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2016
• Subjects: IPY
• Online Access: https://aaltodoc.aalto.fi/handle/123456789/33069; https://doi.org/10.1103/PhysRevB.93.174505

Recently, it was discovered that the ground-state orbital angular momentum in two-dimensional chiral superfluids with pairing symmetry (px+ipy)ν depends on the winding number ν in a striking manner. The ground-state value for the ν=1 case is Lz=N/2 as expected by counting the Cooper pairs, while a dramatic cancellation takes place for ν>1. The origin of the cancellation is associated with the topological edge states that appear in a finite geometry and give rise to a spectral asymmetry. Here, we study the reduction of orbital angular momentum for different potential profiles and pairing strengths, showing that the result Lz=N/2 is robust for ν=1 under all studied circumstances. We study how angular momentum depends on the gap size Δ/EF and obtain the result Lz=ν2N(1-μEF) for ν=2,3. Thus, the gap dependence of Lz for ν Peer reviewed