Enhanced magnetoelectric coupling in two-dimensional hybrid multiferroic heterostructures

Magnetoelectric coupling in insulating multiferroic materials is invaluable for both fundamental research and multifunctional device applications. However, material realization remains a significant challenge. We employ first-principles calculations to predict an enhanced and stacking-robust magnetoelectric coupling in a multiferroic van der Waals heterostructure consisting of ${\mathrm{CrCl}}_{3}$ and ${\mathrm{CuCrP}}_{2}{\mathrm{S}}_{6}$. Within this heterostructure, the intralayer ferroic orders exhibit characteristics of a type-I multiferroic, while the interlayer ferroic orders resemble those of a type-II multiferroic, thus creating a hybrid-type multiferroic. Notably, the interlayer magnetic configuration can be switched upon electric-polarization reversal, while maintaining the insulating property without any nontrivial phase transitions. Our analysis reveals a strongly interfacial spin local-field effect and proximity polarization effect on band alignments. These factors work synergistically to decide the interlayer exchange interaction and drive enhanced magnetoelectric coupling. Finally, we show that this magnetoelectric effect is robust in multilayer structures, exhibiting a dependence on the layer number's parity. This research offers promising prospects for discovering enhanced magnetoelectric couplings in hybrid multiferroic van der Waals heterostructures.