Spin Transport Properties of MnBi₂Te₄-Based Magnetic Tunnel Junctions

The van der Waals heterojunctions, stacking of different two-dimensional materials, have opened unprecedented opportunities to explore new physics and device concepts. Here, combining the density functional theory with non-equilibrium Green's function technique, we systematically investigate the spin-polarized transport properties of van der Waals magnetic tunnel junctions (MTJs), Cu/MnBi₂Te₄/MnBi₂Te₄/Cu and Cu/MnBi₂Te₄/h-BN/n⋅MnBi₂Te₄/Cu (n = 1, 2, 3). It is found that the maximum tunnel magnetoresistance of Cu/MnBi₂Te₄/h-BN/3⋅MnBi₂Te₄/Cu MTJs can reach 162.6%, exceeding the system with only a single layer MnBi₂Te₄. More interestingly, our results indicate that Cu/MnBi₂Te₄/h-BN/n⋅MnBi₂Te₄/Cu (n = 2, 3) MTJs can realize the switching function, while Cu/MnBi₂Te₄/h-BN/3⋅MnBi₂Te₄/Cu MTJs exhibit the negative differential resistance. The Cu/MnBi₂Te₄/h-BN/3⋅MnBi₂Te₄/Cu in the parallel state shows a spin injection efficiency of more than 83.3%. Our theoretical findings of the transport properties will shed light on the possible experimental studies of MnBi₂Te₄-based van der Waals magnetic tunneling junctions.