Large Magnetoresistance in Magnetic Tunnel Junction Based on Ni-Adsorbed CrI3 with Half-Metallicity

Two-dimensional (2D) materials, especially the materials that have intrinsic ferromagnetism (FM), have attracted considerable attention due to their ultraclean interface, controllable stacking order, good flexibility, and other excellent characteristics. However, the low Curie temperature (TC) has limited their practical applications in spintronic devices. Here, we present an approach to enhance the ferromagnetism of the monolayer CrI3 by adsorbing the transition metal atoms (Fe, Co, and Ni) through the first-principles calculation. Interestingly, the Ni-adsorption of monolayer CrI3 has improved the TC to 167 K and introduced the half-metallic feature with a large energy gap of 1.9 eV, which means a high spin polarization rate close to 100%. We further calculate the magnetic tunnel junction formed by the AB stacking bilayer Ni-adsorbed CrI3, which has layer number-dependent magnetic ordering temperature and FM interlayer exchange interaction, by combining density functional theory and the Keldysh nonequilibrium Green’s function. The transport properties calculation results show that the tunnel magnetoresistance (TMR) of this device can reach a large value of 3.94 × 104% due to the half-metallicity induced large spin polarization. The enhanced TC, half-metallicity, and large TMR in magnetic tunnel junctions imply that 2D Ni-adsorbed CrI3 has great potential in practical spintronic applications.