Self-consistent Bogoliubov-de Gennes theory of the vortex lattice state in a two-dimensional strongly type-Ⅱ superconductor at high magnetic fields

摘要

A self-consistent Bogoliubov-de Gennes theory of the vortex lattice state in a 2D strong type-Ⅱ superconductor at high magnetic fields reveals a novel quantum mixed state around the semiclassical H_c2, characterized by a well-defined Landau-Bloch band structure in the quasiparticle spectrum and suppressed order-parameter amplitude, which sharply crossover into the well-known semiclassical (Helfand-Werthamer) results upon decreasing magnetic field. Application to the 2D superconducting state observed recently on the surface of the topological insulator Sb_2Te_3 accounts well for the experimental data, revealing a strong type-Ⅱ superconductor, with unusually low carrier density and very small cyclotron mass, which can be realized only in the strong coupling superconductor limit.