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Study of the Electronic Structure of NiGa 2 S 4 and Extraction of the Spin Hamiltonian Parameters from Ab Initio Calculations
Author(s) -
Pradines Barthélémy,
Lacombe Lionel,
Guihéry Nathalie,
Suaud Nicolas
Publication year - 2018
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201700974
Subject(s) - k nearest neighbors algorithm , hamiltonian (control theory) , ferromagnetism , antiferromagnetism , chemistry , ab initio , condensed matter physics , anisotropy , ab initio quantum chemistry methods , exchange interaction , coupling (piping) , physics , quantum mechanics , molecule , materials science , mathematical optimization , mathematics , organic chemistry , artificial intelligence , computer science , metallurgy
The magnitude of the parameters of the various proposed model Hamiltonians used to model the macroscopic properties of NiGa 2 S 4 and to interpret experimental observations has been the subject of controversy for more than a decade. Both the nature of the relevant operators (magnetic couplings, biquadratic exchange, and anisotropic terms) and the values of their corresponding interactions are far from settled. Through effective Hamiltonian theory and correlated relativistic ab initio calculations, theoretical chemistry can rigorously extract all the required operators and the magnitudes of their corresponding interactions. In this article, we report the values of all relevant interactions. Contrarily to what is often reported, it is shown that: (1) the biquadratic exchange is negligible and smaller than the three‐body terms, (2) the nearest‐neighbor interaction is ferromagnetic and dominant, (3) the next‐nearest‐neighbor coupling is ferromagnetic and small, (4) the next‐next‐nearest‐neighbor coupling is antiferromagnetic and three times smaller than the nearest‐neighbor interaction, and (5) the axial parameter for the local magnetic anisotropy is of the same order of magnitude as the nearest‐neighbor magnetic coupling.