Abstract
By developing models of increasing complexity, we show that a model without single-ion anisotropy (SIA) cannot explain the magnetic properties of moments in the orthorhombically distorted, honeycomb material . In four different models for the magnetization of a single honeycomb layer, the only sources of anisotropy are symmetric exchange interactions along three different bonds , an anisotropic tensor, and a Dzyalloshinskii-Moriya interaction (asymmetric exchange) that produces the observed canted moment along . With 21 parameters, the best such model yields , which is substantially smaller than obtained using a Heisenberg model containing six parameters including easy-axis anisotropy. However, models without SIA fail to reproduce the linear dependence of the magnetization with a field perpendicular to the Ising axis while predicting a saturation magnetization that is far too low. Due to the complex crystal-field environments, we argue that SIA is necessary to study low-symmetry, three-dimensional materials containing ions.
- Received 15 April 2021
- Revised 18 May 2021
- Accepted 1 June 2021
DOI:https://doi.org/10.1103/PhysRevB.103.214440
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