Magnetic susceptibility anisotropies in a two-dimensional quantum Heisenberg antiferromagnet with Dzyaloshinskii-Moriya interactions

TL;DR

This paper investigates the anisotropic magnetic properties of a two-dimensional quantum Heisenberg antiferromagnet with Dzyaloshinskii-Moriya interactions, revealing unusual susceptibility behavior and a crossover in phase transition nature.

Contribution

It provides a theoretical analysis explaining the anisotropic susceptibility and phase crossover in La2CuO4, highlighting its non-ordinary easy-axis antiferromagnetic behavior.

Findings

Magnetic response is anisotropic and differs from conventional easy-axis QHAF.

Neel transition becomes a crossover under perpendicular magnetic field.

Explains unusual magnetic anisotropies in La2CuO4.

Abstract

The magnetic and thermodynamic properties of the two-dimensional quantum Heisenberg antiferromagnet that incorporates both a Dzyaloshinskii-Moriya and pseudo-dipolar interactions are studied within the framework of a generalized nonlinear sigma model (NLSM). We calculate the static uniform susceptibility and sublattice magnetization as a function of temperature and we show that: i) the magnetic-response is anisotropic and differs qualitatively from the expected behavior of a conventional easy-axis QHAF; ii) the Neel second-order phase transition becomes a crossover, for a magnetic field B perpendicular to the CuO(2) layers. We provide a simple and clear explanation for all the recently reported unusual magnetic anisotropies in the low-field susceptibility of La(2)CuO(4), L. N. Lavrov et al., Phys. Rev. Lett. 87, 017007 (2001), and we demonstrate explicitly why La(2)CuO(4) can not be classified as an ordinary easy-axis antiferromagnet.