  The emergence of multiferroic materials, which possess both ferromagnetic
(FM) and ferroelectric (FE) properties, drive advancements in magnetoelectric
applications and the next generation of spintronics. Based on first-principles
calculations, we investigate an engineered two-dimensional multiferroic van der
Waals heterostructures consisting of FM VSiSnN4 monolayer (ML) and fully
hydrogenated FE AlN bilayer. We find that the magnetic anisotropy of VSiSnN4 ML
is tunable between out-of-plane and in-plane and a phase transition between
semiconductor and metal is induced in VSiSnN4/AlN bilayer when the FE
polarization direction of AlN bilayer is reversed. Surprisingly, when the FE
polarization of AlN bilayer is upward, the Curie temperature of VSiSnN4/AlN
bilayer can be significantly increased from 204K to 284K. Such non-volatile and
tunable magnetic anisotropy, Curie temperature and band alignment in
VSiSnN4/AlN multiferroic heterostructure are highly promising for future
low-current operation of data storage and logic devices.
