High-temperature superconductivity in doped antiferromagnets

Abstract

In the context of an effective model for doped antiferromagnets, whereby the charge carriers are treated as hard-core bosons, we demonstrate that the ground state energy close to half-filling 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 Φ 0=2 πℏc/ 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 the charge q in the associated flux quantum might be set equal to 2 e. 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, signalling 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.