Piezovalley effect in altermagnetic Fe2WS4 and Fe2WS2Se2 monolayers

Altermagnets, which arise from the alternating crystal environment and have spontaneous spin-splitting with zero net magnetization, provide a unique opportunity for potential spintronics or valleytronics. Here, we predict two types of stable altermagnets, the Fe2WS4 monolayer and the Janus Fe2WS2Se2 monolayer, based on density functional theory calculations. It is revealed that both monolayers are found to be altermagnetic semiconductors with the valence band maximum and conduction band minimum locating around the high-symmetry point X or Y. Moreover, the altermagnetic order of Fe atom sublattices is related to M110 mirror symmetry. Under uniaxial strains, both monolayers can generate obvious valley polarization and spin polarization due to the broken of the mirror symmetry. Such piezovalley effect in Fe2WS4 and Janus Fe2WS2Se2 monolayers facilitates the design of low-power spintronic devices for information encoding.