The cause for the preferred spin orientation in magnetic systems containing spin-1/2 transition-metal ions was explored by studying the origin of the easy-plane anisotropy of the spin-1/2 Cu2+ ions in CuCl2.2H2O, LiCuVO4, CuCl2 and CuBr2 on the basis of density functional theory and magnetic dipole-dipole energy calculations as well as a perturbation theory treatment of the spin-orbit coupling. We find that the spin orientation observed for these spin-1/2 ions is not caused by their anisotropic spin exchange interactions, nor by their magnetic dipole-dipole interactions, but by the spin-orbit coupling associated with their crystal-field split d-states. Our study also predicts in-plane anisotropy for the Cu2+ ions of Bi2CuO4 and Li2CuO2. The results of our investigations dispel the mistaken belief that magnetic systems with spin-1/2 ions have no magnetic anisotropy induced by spin-orbit coupling.
@article{arxiv.1409.2795,
title = {Most spin-1/2 transition-metal ions do have single ion anisotropy},
author = {Jia Liu and Hyun-Joo Koo and Hongjun Xiang and Reinhard K. Kremer and Myung-Hwan Whangbo},
journal= {arXiv preprint arXiv:1409.2795},
year = {2015}
}
Comments
30 pages, 5 figures; J. Chem. Phys., in press; Typos corrected