Two-dimensional magnetism in kappa-(BEDT-TTF)2Cu[N(CN)2]Cl, a spin-1/2 Heisenberg antiferromagnet with Dzyaloshinskii-Moriya interaction

TL;DR

This study reveals field-induced antiferromagnetic fluctuations and magnetization in a quasi-two-dimensional Heisenberg antiferromagnet with Dzyaloshinskii-Moriya interaction, highlighting the role of anisotropy and intralayer interactions.

Contribution

It demonstrates that the Dzyaloshinskii-Moriya interaction governs anisotropy and that the phase transition temperature is determined by intralayer interactions.

Findings

Field-induced AF fluctuations observed above T_N

Magnetization induced by perpendicular magnetic fields

Interlayer and intralayer correlations distinguished

Abstract

Field-induced antiferromagnetic (AF) fluctuations and magnetization are observed above the (zero-field) ordering temperature, T_N = 23 K by electron spin resonance in kappa-(BEDT-TTF)_2Cu[N(CN)_2]Cl, a quasi two-dimensional antiferromagnet with a large isotropic Heisenberg exchange interaction. The Dzyaloshinskii-Moriya (DM) interaction is the main source of anisotropy, the exchange anisotropy and the interlayer coupling are very weak. The AF magnetization is induced by magnetic fields perpendicular to the DM vector; parallel fields have no effect. The different orientation of the DM vectors and the g factor tensors in adjacent layers allows the distinction between interlayer and intralayer correlations. Magnetic fields induce the AF magnetization independently in adjacent layers. We suggest that the phase transition temperature, T_N is determined by intralayer interactions alone.