Temperature dependence of Vortex Charges in High Temperature Superconductors

TL;DR

This study models how vortex charge in high-temperature superconductors varies with temperature, revealing a transition from negative to positive charge and stripe to isotropic order changes near critical temperatures.

Contribution

It introduces a temperature-dependent model of vortex charge considering antiferromagnetic interactions within a d-wave superconductor, highlighting a first-order transition and order structure changes.

Findings

Vortex charge switches from negative to positive with increasing temperature.

A first-order transition in vortex charge occurs near the critical temperature T_{AF}.

Stripe to isotropic order transition causes vortex charge discontinuity.

Abstract

Using a model Hamiltonian with d-wave superconductivity and competing antiferromagnetic (AF) interactions, the temperature (T) dependence of the vortex charge in high T_c superconductors is investigated by numerically solving the Bogoliubov-de Gennes equations. The strength of the induced AF order inside the vortex core is T dependent. The vortex charge could be negative when the AF order with sufficient strength is present at low temperatures. At higher temperatures, the AF order may be completely suppressed and the vortex charge becomes positive. A first order like transition in the T dependent vortex charge is seen near the critical temperature T_{AF}. For underdoped sample, the spatial profiles of the induced spin-density wave and charge-density wave orders could have stripe like structures at T < T_s, and change to two-dimensional isotropic ones at T > T_s. As a result, a vortex charge discontinuity occurs at T_s.