Absence of Persistent Magnetic Oscillations in Type-II Superconductors

TL;DR

This study uses numerical solutions of the Bogoliubov-deGennes equations to show that magnetic oscillations in type-II superconductors are suppressed when the pairing self-energy surpasses the Landau level separation, contradicting some previous hypotheses.

Contribution

It provides a detailed numerical analysis demonstrating the suppression of magnetic oscillations in type-II superconductors beyond a certain pairing energy threshold.

Findings

Magnetic oscillations are suppressed when pairing self-energy exceeds Landau level separation.

Quasiparticle Landau level broadening and band splittings diminish oscillations.

Arguments for sign change of oscillations are shown to be flawed.

Abstract

We report on a numerical study intended to examine the possibility that magnetic oscillations persist in type II superconductors beyond the point where the pairing self-energy exceeds the normal state Landau level separation. Our work is based on the self-consistent numerical solution for model superconductors of the Bogoliubov-deGennes equations for the vortex lattice state. In the regime where the pairing self-energy is smaller than the cyclotron energy, magnetic oscillations resulting from Landau level quantization are suppressed by the broadening of quasiparticle Landau levels due to the non-uniform order parameter of the vortex lattice state, and by splittings of the quasiparticle bands. Plausible arguments that the latter effect can lead to a sign change of the fundamental harmonic of the magnetic oscillations when the pairing self-energy is comparable to the cyclotron energy are shown to be flawed. Our calculations indicate that magnetic oscillations are strongly suppressed once the pairing self-energy exceeds the Landau level separation.