Theoretical investigation of altermagnetic materials with tunable valley polarization in monolayer Nb2Cl2

Abstract

As an emerging class of materials, altermagnetic materials exhibit intrinsic altermagnetic coupling and spontaneous spin splitting, which have recently led to several new physical phenomena believed to potentially drive the development of frontier spintronic devices. Here we predict a stable Nb₂Cl₂ monolayer with an out-of-plane oriented alternating magnetic ground state and significant valley splitting. Through symmetry analysis, we find that the valleys at the X′ and Y′ points are protected by mirror symmetry M_xy; therefore, multiple couplings, including the piezovalley effect and piezomagnetism, can be realized by uniaxial strain. Accordingly, we propose a logical encoding for information transmission and storage: “−1”, “0”, and “+1”. In addition, we have designed a schematic diagram for experimentally observing the anomalous valley Hall effect. This finding provides a new candidate material for two-dimensional altermagnetic materials in ultrafast, low-power device applications.