CrI3 monolayer: magnetic and electronic behaviors under biaxial strain and external electric field—a first principle study

We have studied the magnetic and electronic behaviors of CrI3 monolayer under biaxial strain and external electric field using first principle calculation. A magnetic phase transition from ferromagnetic to antiferromagnetic state has been observed under a compressing strain of − 6%. The observed influence of biaxial strain on magnetic anisotropy energy is also surprising. Under zero strain it is as high as 0.74 meV/Cr and increases rapidly with compressing strain reaching a value of 1.53 meV/Cr under a compressing strain of − 6%. Moreover, we observe a switching of magnetic easy axis from off-plane to in-plane direction under a tensile strain of 9%. In addition, the bandgap for spin-up ( $${E}_{\mathrm{g}}^{\mathrm{up}})$$ E g up ) from − 10% compressing strain to 10% tensile strain at first increases slowly and exhibits a maximum (~ 0.60 eV) for zero strain. Then it gradually reduces to ~ 0.42 eV for 10% tensile strain. However, the bandgap for spin-down ( $${E}_{\mathrm{g}}^{\mathrm{down}})$$ E g down ) increases monotonically within the entire range and reaches maximum (~ 2.02 eV) for 10% tensile strain. On the other hand, external electric field applied along the off-plane direction (i.e., along c direction) induces significant variations in electronic as well as magnetic (especially MAE) behaviors of CrI3 monolayer. Graphical abstract