Magnetism of Ta dichalcogenide monolayers tuned by strain and hydrogenation

The effects of strain and hydrogenation on the electronic, magnetic, and optical properties of monolayers of Ta based dichalcogenides (TaX₂; X=S, Se, and Te) are investigated using density-functional theory. We predict a complex scenario of strain-dependent magnetic phase transitions involving paramagnetic, ferromagnetic, and modulated antiferromagnetic states. Covering one of the two chalcogenide surfaces with hydrogen switches the antiferromagnetic/nonmagnetic TaX₂ monolayers to a semiconductor, and the optical behavior strongly depends on strain and hydrogenation. Our research opens pathways towards the manipulation of magnetic as well as optical properties for future spintronics and optoelectronics applications.