Giant Rashba effect and nonlinear anomalous Hall conductivity in a two-dimensional molybdenum-based Janus structure

Abstract

Composite quantum materials form a unique class of materials which exhibit more than one apparently distinct quantum phenomenon entangled by common requirement of different symmetries in a single material. In search of composite quantum phases in two dimensions, we investigate the electronic properties of computationally designed transition-metal carbide Janus compounds, with strong spin-orbit coupling and inversion symmetry broken by asymmetric surface passivation. The ab initio calculated electronic structure of these Janus structures, show giant Rashba effect with Rashba coefficients as large as $\ensuremath{\approx}25\phantom{\rule{4pt}{0ex}}\mathrm{eV}\phantom{\rule{0.16em}{0ex}}\AA{}$. Interestingly, the same Janus structures are shown to be potential candidates to exhibit nonlinear anomalous Hall conductivity owing to the nonzero Berry curvature on the nonequilibrium Fermi surface. Our computational study predicts that such Janus structures can be promising platform for exploring intertwined quantum phenomena in a single two-dimensional system. The two-dimensionality of the proposed systems make them ideally suited for device fabrication with technological implication of composite quantum materials.