Strain-induced altermagnetism to ferromagnetism transition in monolayerCr2Si2S3Se3

Magnetic phase transition, especially that involving altermagnets, can provide diverse mechanisms and ideas for the development of multifunctional materials. Here, we employ first-principles calculations to predict the altermagnetic monolayerCr2Si2S3Se3with excellent stability. TheCr2Si2S3Se3is an indirect bandgap semiconductor, which featuresi-wave spin splitting symmetry due to the spin layer group of13¯2m. Tensile strain can induce a phase transition from altermagnetism to ferromagnetism, with the critical strain ratioa/a0being 1.02. This phase transition causes the spin splitting to evolve from momentum-dependent one to global one (i-wave tos-wave). When spin-orbital coupling is taken into account, the magnetic phase transition is also accompanied by the disappearance of the valley polarization between the -KandKvalleys. Our works broaden the scope of magnetic phase transitions and highlight the connection with valley polarization, which is beneficial for the integration of spintronics and valleytronics.