Strain Tunability of Perpendicular Magnetic Anisotropy in van der Waals Ferromagnets VI3

Layered ferromagnets with strong magnetic anisotropy energy (MAE) have special applications in nanoscale memory elements in electronic circuits. Here, we report a strain tunability of perpendicular magnetic anisotropy in van der Waals (vdW) ferromagnets VI₃ using magnetic circular dichroism measurements. For an unstrained flake, the M-H curve shows a rectangular-shaped hysteresis loop with a large coercivity (1.775 T at 10 K) and remanent magnetization. Furthermore, the coercivity can be enhanced to a maximum of 2.6 T under a 3.8% external in-plane tensile strain. Our DFT calculations show that the increased MAE under strain contributes to the enhancement of coercivity. Meanwhile, the strain tunability on the coercivity of CrI₃, with a similar crystal structure, is limited. The main reason is the strong spin-orbit coupling in V³⁺ in VI₆ octahedra in comparison with that in Cr³⁺. The strain tunability of coercivity in VI₃ flakes highlights its potential for integration into vdW heterostructures.