Role of spin-orbit coupling on crystal-field splitting and phase-stability of rare-earth based layered intermetallic

Abstract

Layered and incommensurate heterostructures have attracted much attention for the occurrence of superconductivity and charge density waves with the possibility of intercalating foreign atoms. However, lanthanide-based heterostructures where (EuxSm1-x)S and TaS2 are alternatively stacked have been scarcely investigated. In this work, we performed phase stability, bonding behavior and electronic-structure analysis of (EuxSm1-x)TaS3 using first-principles density-functional theory methods. Our phase stability analysis suggests 50 at.% solubility of Eu in (EuxSm1-x)TaS3 compared to Eu solubility in all proportions in cubic SmS. The instability of Eu beyond 50 at.% in (EuxSm1-x)TaS3 was attributed to higher density of Eu-4f states at the Fermi-level. Based on band position calculated from spin-orbit coupling effect, we constructed a qualitative schematic of possible crystal-field analysis. The local change in bond-length and bond-angle around Eu-S in (EuxSm1-x)TaS3 correlate well with our crystal-field analysis. We believe that quantum mechanical insights provided in this work will be useful to understand other complex heterostructures.