Relativistic topological molecular descriptors of metal trihalides

Abstract

A series of novel two-dimensional, metal trihalides MX3, have been explored recently because of their unusual Dirac half-metallicity, intriguing topological spintronic properties arising from both inherent magnetization and large relativistic spin-orbit coupling effects exhibited by these 2D metal halides. Moreover due to large spin-orbit coupling which results in unusual band gaps combined with their stopping power and higher Curie temperature, 2D materials such as BiI3 find important applications in room temperature radiation detectors. Hence the present work is devoted to relativistic topological characterization of two classes of 2D trihalides. We outline techniques for incorporation of relativistic parameters into topological expression through 2-component Wannier spinors obtained by localization methods. Mathematical expressions of several structurally based topological indices are proposed in terms of parameters that can be derived from relativistic quantum computations including spin-orbit coupling for the first time.