Magnetoelasticity in CrXTe₃ (X = C, Si) van der Waals Heterobilayers

Magnetism in reduced dimensions has been of sustained interest due to the rich phase diagram as a response toward varying crystal symmetries and external perturbations. The recent observation of a long-range ferromagnetic order in two-dimensional (2D) van der Waals crystals with uniaxial magnetic anisotropy has provided tremendous impetus in this quest. Here, we investigate heterobilayers of 2D magnetic transition-metal trichalcogenides within first-principles calculations by stacking antiferromagnetic CrCTe3 and ferromagnetic CrSiTe3. The magnetic properties in this class of systems stem from their crystal symmetries and consequent superexchange paths between neighboring magnetic centers. The lattice mismatch between the two layers induces intrinsic strain and results in overall antiferromagnetic spin alignments in this heterobilayer. However, a gradual increase in tensile strain only up to 4% changes the crystal parameters and leads to various magnetic ground states. This magnetoelastic behavior results in interesting electronic and optoelectronic properties, e.g., layer-selective spin current and exciton dissociation in the heterobilayer, which can be exploited for advanced spintronic and photovoltaic applications. Furthermore, the observation of an unprecedented metamagnetic phase transition in this class of systems will tempt further fundamental explorations.