Coupled $S=1/2$ Heisenberg antiferromagnetic chains in an effective staggered field

TL;DR

This paper systematically studies coupled S=1/2 Heisenberg antiferromagnetic chains under an effective staggered field, analyzing phase transitions and gap behaviors in higher-dimensional spin systems through analytical methods.

Contribution

It introduces a combined analytical approach using mean-field and chain mean-field theories to explore phase transitions and gap behaviors in coupled spin chains under staggered fields.

Findings

Prediction of a phase transition when staggered field and inter-chain interaction compete.

Different behaviors of induced gaps in competitive vs. non-competitive cases.

Refined phase diagram with chain mean-field theory showing smaller ordered phase region.

Abstract

We present a systematic study of coupled $S=1/2$ Heisenberg antiferromagnetic chains in an effective staggered field. We investigate several effects of the staggered field in the {\em higher} ({\em two or three}) {\em dimensional} spin system analytically. In particular, in the case where the staggered field and the inter-chain interaction compete with each other, we predict, using mean-field theory, a characteristic phase transition. The spin-wave theory predicts that the behavior of the gaps induced by the staggered field is different between the competitive case and the non-competitive case. When the inter-chain interactions are sufficiently weak, we can improve the mean-field phase diagram by using chain mean-field theory and the analytical results of field theories. The ordered phase region predicted by the chain mean-field theory is substantially smaller than that by the mean-field theory.