Tight binding prediction of the α-Gd2S3 magnetic structure

Spin-dependent extended Hückel tight binding (EHTB) calculations were carried out for the magnetic solid Gd2S3 by considering 20 different variations in the ordering of the 4f7 moments. The tight-binding calculations are used to interpolate the band structure of a nonmagnetic congener (Y2S3) and the 4f/5d,6s exchange interactions are introduced as perturbations via the introduction of spin-dependent Hdd and Hss parameters. The calculations predict that Gd2S3 adopts an antiferromagnetic ordering of the 4f7 moments that is consistent with published neutron diffraction results. Our attempt to account for the calculated energies of the spin patterns using an Ising model was unsuccessful.