Strain-adjustable spintronics with robust polarity in Janus FeClS

The monolayer Janus FeClS, whose mirror inversion symmetry is broken due to its different non-metallic atomic compositions, exhibits spontaneous polarity and obvious spin polarization and has unique half-metal properties different from the corresponding pure monolayer FeCl2 and FeS2, that is, the spin-up band appears as a semiconductor and the spin-down band appears as a metal. As the most common and effective means of structure and performance regulation, biaxial strain is applied to monolayer FeClS for study. Importantly, the strain-induced crystal structure changes cause different inter-hybridization of Fe-3d electron orbitals in Janus FeClS, which leads to changes in electronic structures. In particular, the half-metal properties, dipole moments, and magnetic axis orientation of monolayer Janus FeClS remain basically unchanged under a certain degree of tensile and compressive strain, and the critical strain degree is basically the same when these properties are changed, indicating that Janus FeClS has a robust electronic structure and polarity. In addition, the magnetic moment and the absorption of visible light in monolayer FeClS are also regulated by biaxial strain. Therefore, this study expands the prospect and direction for the effective use and regulation of the excellent spin polarization characteristics of polar two-dimensional materials.