Absence of Dipole Transitions in Vortices of Type II Superconductors

TL;DR

This paper investigates the microscopic response of vortices in type II superconductors to time-dependent fields, revealing that dipole transitions are hidden and instead vortex motion exhibits resonance at specific frequencies.

Contribution

It derives an equation of motion for vortex dynamics at non-zero frequencies and explains the absence of dipole transitions due to the self-consistent vortex potential.

Findings

Vortex response shows a resonance at transition frequency.

Dipole transitions are hidden by self-consistent vortex potential.

Results are relevant for materials like NbSe2 and high-temperature superconductors.

Abstract

The response of a single vortex to a time dependent field is examined microscopically and an equation of motion for vortex motion at non-zero frequencies is derived. Of interest are frequencies near $\Delta^{2}/E_{F}$, where $\Delta$ is the bulk energy gap and $E_{F}$ is the fermi energy. The low temperature, clean, extreme type II limit and maintaining of equilibrium with the lattice are assumed. A simplification occurs for large planar mass anisotropy. Thus the results may be pertinent to materials such as $NbSe_2$ and high temperature superconductors. The expected dipole transition between core states is hidden because of the self consistent nature of the vortex potential. Instead the vortex itself moves and has a resonance at the frequency of the transition.