  Two-dimensional CrI3 has attracted much attention as it is reported to be a
ferromagnetic semiconductor with the Curie temperature around 45K. By
performing first-principles calculations, we find that the magnetic ground
state of CrI3 is variable under biaxial strain. Our theoretical investigations
show that the ground state of monolayer CrI3 is ferromagnetic under
compression, but becomes antiferromagnetic under tension. Particularly, the
transition occurs under a feasible in-plane strain around 1.8%. Accompanied by
the transition of the magnetic ground state, it undergoes a transition from
magnetic-metal to half-metal to half-semiconductor to spin-relevant
semiconductor when strain varies from -15% to 10%. We attribute these
transitions to the variation of the d-orbitals of Cr atoms and the p-orbitals
of I atoms. Generally, we report a series of magnetic and electronic phase
transition in strained CrI3, which will help both theoretical and experimental
researchers for further understanding of the tunable electronic and magnetic
properties of CrI3 and their analogous.
