Tunable magnetic behavior, conductivity and valley polarization in two-dimensional YMnO3/2H-VS2 multiferroic heterostructures

Manipulation of spin-valleys plays a key role in spintronics and valleytronics. The magnetoelectric coupling effect in the two-dimensional (2D) ferroelectricity/ferromagnetism heterostructures offers a feasible way to achieve the modulation of magnetic properties and valley degrees of freedom. In this work, the electronic structure, magnetism and valley polarization of YMnO3/2H-VS2 multiferroic heterostructures are investigated in detail by first-principles calculations. The results show that the ferromagnetism, valley polarization and con-ductivity of 2H-VS2 layer can be largely altered by the YMnO3 substrate with different terminations. The valley polarization can achieve a maximum modulation of 112.5 meV for the YMnO3/2H-VS2 heterostructure with MnO-termination when the ferroelectric polarization is reversed. On the other hand, the direction of magnetic moment of V atom in the 2H-VS2 layer can be effectively adjusted in the O-2-and Y-terminated configurations by altering the ferroelectric polarization, which can be attributed to the magnetic interaction between the ferro-magnetic 2H-VS2 and ferroelectric YMnO3. Compared with the case of isolated 2H-VS2 monolayer, 2H-VS2 ex-hibits p-type doping character in O-and Y-terminated configurations. The valley and direct bandgap semiconductor properties of 2H-VS2 monolayer are preserved for all configurations. Moreover, the O-S distance can be considered as a main factor for regulating the valley polarization by affecting orbital hybridization. These results exhibit new coupling effects between ferromagnetism, ferroelectronics and ferrovalley by the electrical control of spin-valleys behaviors, which provides a new platform for developing nonvolatile spintronic and valleytronic devices.