Temperature dependence of vortex charges in high-temperature superconductors

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 an underdoped sample, the spatial profiles of the induced spin-density wave and the charge-density wave orders could have stripelike 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.