Crystal structures and electronic and magnetic properties of Janus bilayer Cl[formula omitted]Cr[formula omitted]I[formula omitted]

Abstract

Two-dimensional (2D) magnetic material CrI3 has aroused extensive attention, because it could provide a new platform for investigating the relations between crystal structures and electronic and magnetic properties. Here, we study crystal structures and electronic and magnetic properties of three configurations (Cl-Cl I-I and Cl-I) of Janus bilayer Cl3Cr2I3 with two stacking orders (AB and AA1/3) by using the first principles approach incorporating the spin–orbit coupling (SOC) effect and the dipole correction. It is found that the spin polarization and the SOC effect can expand the lattice constant and the interlayer distance (ID) of the three configurations. Especially, the ID of the I-I configuration is 1 Å larger than that of the Cl-Cl configuration. The total energy calculation results show that the atomic configuration, the SOC effect and the stacking order play an important role in determining the magnetic ground states of the Janus layers. Our results indicate the atomic configurations of the Janus bilayers are not conducive to the increase of critical temperature. Interestingly, the Cl-I configuration has a vertical dipole moment, and its AFM state has large spin splitting. It is revealed that the non-periodic structure, the symmetry breaking of the average potential and the weak interlayer interaction lead to the vertical dipole moment and the abnormal AFM state that is not the most stable state.