Strain modulation of the spin-valley polarization in monolayer manganese chalcogenophosphates alloys.

Inspired by the profound physical connotations and potential applications of the spintronics and valleytronics, two-dimensional (2D) monolayer manganese chalcogenophosphates alloys are constructed, and the strain modulated spin-valley characteristics are investigated through the first principles calculations. For both the MnFePS3and MnFePSe3, the conductivity can be tuned reversibly between semiconductive and half-metallic, while and magnetic stability is controllable between ferromagnetism and antiferromagnetism. Large valley splitting of up to 1000 meV is achieved in MnFePS3under a -4% strain. Simultaneous spin splitting of 219 meV and valley splitting of 160 meV are acquired in MnFePS3under a 4% strain. Strain tunable magnetic moment and interaction between Mn, Fe and S/Se atoms are revealed as the internal mechanisms of controlling the magnetic stability, spin and valley polarizations in the two structures. All the findings in this work provide a strategy for the manipulation of spin and valley degrees of freedom in 2D magnetic materials.