Magnetic properties of the quasi-two-dimensional S = 1/2 Heisenberg antiferromagnet [Cu(pyz)2(HF2)]PF6

TL;DR

This study investigates the magnetic properties of a quasi-two-dimensional S=1/2 Heisenberg antiferromagnet, revealing details about its magnetic structure, anisotropy, and the influence of two-dimensional correlations despite three-dimensional ordering.

Contribution

First detailed experimental analysis of [Cu(pyz)2(HF2)]PF6's magnetic properties, including ESR and magnetization, with quantitative estimates of anisotropy and interlayer interactions.

Findings

Confirmed collinear magnetic structure with easy-plane anisotropy

Determined anisotropy/exchange ratio A/J = 0.003

Estimated inter/intra-plane exchange ratio J'/J = 1/16

Abstract

We report on high-field magnetization, specific-heat and electron spin resonance (ESR) studies of the quasi-two-dimensional spin-1/2 Heisenberg antiferromagnet [Cu(pyz)2(HF2)]PF6. The frequency-field diagram of ESR modes below TN = 4.38 K is described in the frame of the meanfield theory, confirming a collinear magnetic structure with an easy-plane anisotropy. The obtained results allowed us to determine the anisotropy/exchange interaction ratio, A/J = 0.003, and the upper limit for the inter/intra-plane exchange-interaction ratio, J'/J = 1/16. It is argued that despite the onset of 3D long-range magnetic ordering the magnetic properties of this material (including high-magnetic-field magnetization and non-monotonic field dependence of the Neel temperature) are strongly affected by two-dimensional spin correlations.