Flux quantization and superfluid weight in doped antiferromagnets

TL;DR

This paper demonstrates flux quantization and superfluid weight in doped antiferromagnets modeled by a t-t'-J model, revealing a connection to high-temperature superconductivity phenomena.

Contribution

It shows flux quantization and superfluid weight in a doped antiferromagnet model, linking these to superconducting transition temperature and high-Tc cuprates.

Findings

Flux quantization occurs with a period equal to the flux quantum.

Superfluid weight D_s is finite in the metallic antiferromagnetic phase.

T_c depends linearly on D_s, consistent with Kosterlitz-Thouless transition.

Abstract

Doped antiferromagnets, described by a t-t'-J model and a suitable 1/N expansion, exhibit a metallic phase-modulated antiferromagnetic ground state close to half-filling. Here we demonstrate that the energy of latter state is an even periodic function of the external magnetic flux threading the square lattice in an Aharonov-Bohm geometry. The period is equal to the flux quantum $\Phi_{0}=2\pi\hbar c/q$ entering the Peierls phase factor of the hopping matrix elements. Thus flux quantization and a concomitant finite value of superfluid weight D_s occur along with metallic antiferromagnetism. We argue that in the context of the present effective model, whereby carriers are treated as hard-core bosons, the charge q in the associated flux quantum might be set equal to 2e. Finally, the superconducting transition temperature T_c is related to D_s linearly, in accordance to the generic Kosterlitz-Thouless type of transition in a two-dimensional system, signaling the coherence of the phase fluctuations of the condensate. The calculated dependence of T_c on hole concentration is qualitatively similar to that observed in the high-temperature superconducting cuprates.