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

Article

关键词: HE-3-A;    PHASE;    LIQUID-HE-3;   

DOI  :  10.1103/PhysRevB.93.174505

来源: SCIE

【 摘 要 】

Recently, it was discovered that the ground-state orbital angular momentum in two-dimensional chiral superfluids with pairing symmetry (px + ipy)(nu) depends on the winding number nu in a striking manner. The ground-state value for the nu = 1 case is L-z = (h) over barN/2 as expected by counting the Cooper pairs, while a dramatic cancellation takes place for nu > 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 L-z = (h) over barN/2 is robust for nu = 1 under all studied circumstances. We study how angular momentum depends on the gap size Delta/E-F and obtain the result L-z = (h) over bar nu/2N(1 -mu/E-F) for nu = 2,3. Thus, the gap dependence of L-z for nu < 4 enters at most through the chemical potential while nu >= 4 is qualitatively different. In addition, we generalize the spectral asymmetry arguments to total angular momentum in the ground state of triplet superfluids where due to a spin-orbit coupling L-z is not a good quantum number. We find that the ground-state total angular momentum also behaves very differently depending on total angular momentum of the Cooper pairs.

【 授权许可】

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