Abstract
Using ab initio density functional theory, we study the electronic and magnetic properties of the van der Waals chain material OsCl4. In the nonmagnetic state, a strongly anisotropic band structure was observed, in agreement with its anticipated one-dimensional crystal geometry. Based on Wannier functions, we found that the four electrons of the 5d Os atom form a low-spin Sโ=โ1 state, with a large crystal field between the ๐๐ฅ๐ง/๐ฆ๐ง and dxy orbitals, corresponding to a strong JahnโTeller distortion (๐3<โ0). As a consequence, the magnetic properties are mainly contributed by the ๐๐ฅ๐ง/๐ฆ๐ง states. Furthermore, when a Mott gap develops after the introduction of the Hubbard U and Hund coupling J, we found that the staggered spin order is the most likely magnetic state, namely, spins arranged as (โ-โ-โ-โ) with ฯ wavevector along the chain. In addition, the energy differences between various spin states are small, suggesting a weak magnetic exchange coupling along the chain. Our results provide guidance to experimentalists and theorists working on quasi-one-dimensional osmium halides chain materials.
