Strain-induced multifunctional altermagnetism in a Janus material

Altermagnetism, an emerging magnetic phase exhibiting spin-polarized electronic bands and zero net magnetization, has attracted significant attention for next-generation spintronics. However, experimental realizations of such materials remain scarce, necessitating reliable methods for inducing phase transitions from conventional magnetic states. Here, we propose a strain-driven ferromagnetic-to-altermagnetic (FM-AM) phase transition in 1T Janus CrTeBr. Through spin symmetry analysis and first-principles calculations, we reveal that a tensile strain of approximately 2% triggers this transition. The resultant AM phase exhibits nonrelativistic spin splitting (127.3 meV) while preserving zero net magnetization, with the spin splitting, spontaneous electric polarization, and valley polarization highly tunable via stacking engineering. Our work provides an experimentally feasible pathway to realize altermagnetism and offers a general strategy applicable to other FM systems, accelerating development of this burgeoning field.