Effective action approach to a bi-layer frustrated antiferromagnet

TL;DR

This paper investigates a bi-layer quantum frustrated antiferromagnet using an effective action approach, deriving a phase diagram that shows how interlayer coupling and in-plane frustration influence magnetic ordering.

Contribution

It introduces an effective action based on the O(3) non-linear sigma model to analyze the phase diagram of a bi-layer frustrated antiferromagnet, providing new insights into critical coupling values.

Findings

Critical interlayer coupling decreases with increased in-plane frustration.

Estimated critical J2 value for single-layer model is 0.19 J1.

Phase diagram shows the relationship between frustration and magnetic order.

Abstract

A bi-layer quantum frustrated antiferromagnet is studied using an effective action approach. The action derived from the microscopical Hamiltonian has the form of the O(3) non-linear sigma model. It is solved in the mean field approximation with the ultraviolet cut off chosen to fit numerical results. The obtained phase diagram displays a decrease in the critical value of interlayer coupling with increase of in-plane frustration. The critical point for a single-layer frustrated antiferromagnet (the J1-J2 model) is estimated to be J_{2c} = 0.19 J_1.