Spiral order induced by distortion in frustrated square-lattice antiferromagnet

TL;DR

This paper investigates how lattice distortions in a frustrated square-lattice antiferromagnet can induce incommensurate spiral magnetic order, especially near the boundary of collinear antiferromagnetic states, with implications for doped cuprates.

Contribution

It demonstrates that weak lattice distortions can stabilize incommensurate spiral phases in frustrated antiferromagnets close to the collinear phase boundary.

Findings

Lattice distortions lower the energy of spiral states near ( extpi, extpi).

Incommensurate spiral order can be stabilized by superstructural modulations.

Results suggest relevance to magnetic behavior in doped cuprates.

Abstract

In a strongly frustrated square-lattice antiferromagnet with diagonal coupling J', for J/(2J') < 1, an incommensurate spiral state with propagation vector Q = (\pi +/- \delta, \pi +/- \delta) near (\pi,\pi) competes closely with the Neel collinear antiferromagnetic ground state. For classical Heisenberg spins the energy of the spiral state can be lowered as it adapts to the distortion of the crystal lattice. As a result, a weak superstructural modulation such as exist in doped cuprates might stabilize an incommensurate spiral phase for some range of the parameter J/(2J') close to 1.