Tunable Tunneling Magnetoresistance in van der Waals Magnetic Tunnel Junctions with 1<b><i>T</i></b>-CrTe_<b>2</b> Electrodes

Abstract

Two-dimensional (2D) van der Waals (vdW) heterostructures have opened new avenues for spintronic applications with novel properties. Here, by density functional theory calculations, we investigated the spin-dependent transport in vdW magnetic tunnel junctions (MTJs) composed of 1<i>T</i>-CrTe₂ ferromagnetic electrodes. Meanwhile, graphene and <i>h</i>-BN are employed as tunnel barriers. It has been found that the tunneling magnetoresistance (TMR) effects of two types of vdW MTJs present analogous trends: thicknesses of barriers have a great influence on the TMR ratios, which reach up to the maximum when barriers increase to five monolayers. However, despite the similarity, the graphene-barrier junction is more promising for optimization. Through observing the energy-resolved transmission spectra of vdW MTJs, we noticed that TMR ratios of graphene-barrier junctions are tunable and could be enhanced through tuning the position of Fermi energy. Therefore, we successfully realized the TMR optimization by substitutional doping. When substituting one carbon atom with one boron atom in the graphene barrier, TMR ratios are drastically improved, and a TMR ratio as high as 6962% could be obtained in the doped seven-monolayer-barrier junction. Our results pave the way for vdW MTJ applications in spintronics.