Tunable spin/valley splitting and multiple Hall effects in interlayer coupling-dependent SVSiN2 multiferroic bilayers

Compared to two-dimensional (2D) monolayered ferrovalley semiconductors (FVS), 2D FVS bilayers with interlayer coupling are more sensitive to external electric fields, and their applications for valleytronics and spintronics are very promising. Using first principles calculations, we demonstrate that the valley and spin degeneracy in the SVSiN2 bilayer can be manipulated through different interlayer magnetic orders and stackings. Compared with its monolayer counterpart, the valley/spin polarization in the SVSiN2 bilayer is highly tunable by electric field. Specifically, different stackings, magnetic orders, and vertical electric fields could result in various transport behaviors for the SVSiN2 bilayer, including spin Hall current, valley Hall current, and anomalous Hall current with different valley, spin, and layer combinations. In addition, the AB and AC stacked SVSiN2 bilayers with mirror symmetry breaking exhibit the coexistence of ferrovalley and ferroelectric polarization. Our work provides a theoretical foundation and an effective route to manipulate valley/spin in 2D bilayers.