title: Orbital angular momentum and spectral flow in two-dimensional chiral superfluids.
abstract: We study the orbital angular momentum (OAM) L_{z} in two-dimensional chiral (p_{x}+ip_{y})^{ν}-wave superfluids (SFs) of N fermions on a disk at zero temperature, in terms of spectral asymmetry and spectral flow. It is shown that L_{z}=νN/2 for any integer ν, in the Bose-Einstein condensation regime. In contrast, in the BCS limit, while the OAM is L_{z}=N/2 for the p+ip-wave SF, for chiral SFs with ν≥2, the OAM is remarkably suppressed as L_{z}=N×O(Δ_{0}/ϵ_{F})≪N, where Δ_{0} is the gap amplitude and ϵ_{F} is the Fermi energy. We demonstrate that the difference between the p+ip-wave SF and the other chiral SFs in the BCS regimes originates from the nature of edge modes and related depairing effects.
authors.affiliation: Institute for Solid State Physics, The University of Tokyo, Kashiwa 277-8581, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Tada
authors.affiliation: Institute for Solid State Physics, The University of Tokyo, Kashiwa 277-8581, Japan.|Institute for Advanced Study, Tsinghua University, Beijing 100084, China.
authors.forename: Wenxing
authors.initials: W
authors.lastname: Nie
authors.affiliation: Institute for Solid State Physics, The University of Tokyo, Kashiwa 277-8581, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Oshikawa