Spin Inversion Enforced by Crystal Symmetry in Ferroelastic Altermagnets

The realm of spintronics has witnessed a profound surge in fascination towards altermagnetism, fueled by groundbreaking predictions and a myriad of promising applications. Here, we propose a novel multiferroic mechanism between ferroelasticity and altermagnetism based on symmetry analysis. Through first-principles calculations, we predict monolayer Janus tetragonal V_{2}OS and series of related materials as promising material candidates, where ferroelastic strain breaks the intrinsic symmetry of altermagnetism, transforming it into a compensated ferrimagnetic state and enabling the manipulation of spin-polarized states through ferroelastic switching. The magnetic order of monolayer V_{2}OS could survive above room temperature with manageable ferroelastic switching energy, indicating immense potential for practical applications. Furthermore, by calculating the in-plane spin conductance and simulating magnetic tunnel junctions, we demonstrate that V_{2}OS can discriminate spin states along both in-plane and out-of-plane directions. These findings open up novel avenues for two-dimensional altermagnetism-based spintronics, particularly in the realm of high-density, low-power consumption, and non-volatile information storage devices.