Strain-dependent electronic, magnetic, and optical properties of a van der Waals CrI₃/VI₃ heterostructure: a first principles study

Strain engineering can induce remarkable changes in the intrinsic properties of parent two-dimensional (2D) materials. In this study we perform first-principles calculations to investigate the effects of both tensile and compressive strain on the different properties of a 2D ferromagnetic (FM) van der Waals (vdW) CrI₃/VI₃ heterostructure material, where the energetically more stable AB stacking is used. Interestingly, tensile strain enhances the FM ground state, while compressive strain reduces the FM properties. Besides, we report a substantial improvement in the magnetic, electronic and valleytronics properties of the vdW CrI₃/VI₃ heterostructure. Interestingly, the ferromagnetism of the vdW CrI₃/VI₃ heterostructure remains unchanged under biaxial strain. We also used Monte Carlo simulations to investigate the biaxial strain effect above the Curie temperature. Including spin-orbit coupling (SOC), we found a peculiar change in the band structure. Besides, the SOC effect causes a splitting of bands at the high-symmetry points <i>K</i> and <i>K</i>', which results in a large change in the valleytronics but also reduces the band gap of the vdW CrI₃/VI₃ heterostructure subsequently with biaxial strain. At the end we also investigated the optical properties. Therefore, our findings suggest new design strategies for constructing a FM CrI₃/VI₃ vdW heterostructure for prominent valleytronics, opto-electronic and spintronic device applications.