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.