Superconductivity in High Magnetic Field:Excitation Spectrum and Tunneling Properties

TL;DR

This paper investigates the excitation spectrum and tunneling properties of type-II superconductors in high magnetic fields, revealing a transition from gapless to gapped states and their implications for thermodynamic and tunneling behaviors.

Contribution

It demonstrates that high magnetic fields induce a gapless excitation spectrum in type-II superconductors, with a detailed analysis of the transition to gapped states at lower fields.

Findings

The excitation spectrum becomes gapless in high magnetic fields.

Gaps open at the Fermi surface when the field decreases below a critical value.

Algebraic temperature dependence in thermodynamic functions and tunneling conductance observed.

Abstract

The quasiparticle excitation spectrum of a type-II superconductor placed in high magnetic field is shown to be gapless. The gap turns to zero at the points in the MBZ which are in correspondence with the vortex lattice in real space. When the field decreases below certain critical value, branch crossing occur and gaps starts opening up at the Fermi surface.The strong dispersion around gapless points leads to algebraic temperature dependence in the thermodynamic functions and the algebraic voltage dependence in the tunneling conductance between the microscope tip and superconductor in an STM experiment.