Study of the electronic Structure of NiGa2S4 and extraction of the spin Hamiltonian parameters from ab initio calculations

5 years ago

Study of the electronic Structure of NiGa2S4 and extraction of the spin Hamiltonian parameters from ab initio calculations

Barthélémy Pradines, Nicolas Suaud, Nathalie Guihery, Lionel Lacombe

The magnitude of the parameters of the various proposed model Hamiltonians used to model the macroscopic properties of the NiGa2S4 material and to interpret experimental observations is subject to controversy for more than a decade. Both the nature of the relevant operators (magnetic couplings, biquadratic exchange, anisotropic terms) and the values of their corresponding interactions are far from being settled. Owing to the effective Hamiltonian theory and correlated relativistic ab initio calculations, theoretical chemistry can rigorously extract all required operators and the magnitude of their corresponding interactions. In this article, we report the values of all relevant interactions. Contrarily to what is often written, it is shown that: i) the biquadratic exchange is negligible and smaller than the three-body terms, ii) the nearest neighbor interaction is ferromagnetic and dominant, iii) the next nearest neighbor coupling is ferromagnetic and small, iv) the next next nearest neighbor coupling is antiferromagnetic and three times smaller than the nearest neighbor interaction and v) last but not least the local magnetic anisotropy axial parameter is of the same order of magnitude as the nearest neighbor magnetic coupling.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/ejic.201700974