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 Sβ=β1 state, with a large crystal field between the ππ₯π§/π¦π§ and dxy orbitals, corresponding to a strong JahnβTeller distortion (π3<β0). As a consequence, the magnetic properties are mainly contributed by the ππ₯π§/π¦π§ 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 (β-β-β-β) with Ο 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.
