Strain-engineered anomalous Nernst effect and layer-polarized anomalous Hall response in RuBr2

Abstract

The anomalous Nernst effect (ANE) has gained attention as a viable mechanism for transverse thermoelectric energy conversion. In this work, we systematically investigate the impact of strain on the ANE response in both monolayer and bilayer RuBr2. We demonstrate that biaxial strain induces non-crossing points in the electronic band structure, which act as Berry curvature hotspots. These features significantly enhance the intrinsic contributions to both the anomalous Hall and Nernst conductivities. This results in an enhanced anomalous Nernst coefficient (N) in the bilayer, along with an improved thermoelectric figure of merit (ZTANE). These findings indicate that strain provides an effective means to optimize ANE performance in RuBr2. Additionally, we identify a layer-polarized anomalous Hall effect (LP-AHE) in bilayer RuBr2, originating from layer-dependent Berry curvature and spontaneous valley polarization. The obtained valley polarization in the valence and conduction bands is tunable through both sliding ferroelectricity and strain. The combination of strain-modulated ANE response and LP-AHE establishes RuBr2 as a promising candidate for next-generation energy-harvesting and multiferroic applications.