Multipiezo effect in altermagnet V2SeO monolayer at high temperature

Altermagnetism, characterized by a compensated magnetic order with momentum-dependent spin splitting, has recently gained attention as a potential platform for advanced spintronic technologies. When combined with multifunctional responses such as piezoelectricity, piezovalley, and piezomagnetism, exciting possibilities for strain-controlled magneto-electronic applications are opened. In this study, we investigated the Janus monolayer V 2 SeO, a two-dimensional altermagnetic material, using first-principles calculations. A high Néel temperature of 950 K confirmed the antiferromagnetic nature of the ground state. The material is thermodynamically and dynamically stable. Furthermore, V 2 SeO exhibits a direct band gap of 0.34 eV and non-relativistic spin-splitting (∼0.26 eV) at high-symmetry points, confirming its altermagnetic character. The broken mirror symmetry of the Janus structure enabled an out-of-plane piezoelectric effect, with calculated coefficients of e 31 = 49.90 pC/m and d31 = 0.25 pm/V. A strain-induced piezovalley effect yields a large valley polarization of up to 131 meV, while doping under strain induces a finite piezomagnetic response. These coexisting properties, including altermagnetism, piezoelectricity, piezovalley, and piezomagnetism, position monolayer V 2 SeO as a strong candidate for future strain-tunable spintronic and valleytronic devices applications. Its potential synthesis via exfoliation or chemical vapor deposition makes it experimentally accessible.