Abstract
Two-dimensional (2D) van der Waals (vdW) magnetic semiconductors have attracted wide interest for their promising application in next-generation spintronic devices. We investigate the scaling behavior of the tunnel magnetoresistance (TMR) of the Ag/n-layer CrI3/Ag and graphite/n-layer CrI3/graphite magnetic tunnel junctions (MTJs) by using ab initio quantum-transport simulations. The calculated monotonic increasing TMR of the graphite/n-layer CrI3/graphite MTJ with n = 2-4 at zero bias agrees with the experimental value. The TMR of the Ag/n-layer CrI3/Ag MTJ generally increases with the tunnel-barrier layer number, n, that is, from 200% (2-layer CrI3) to a record 10(9) % value (12-layer CrI3) at zero bias but has an odd-even oscillation when n < 7. When we apply a bias voltage to the Ag/2-layer CrI3/Ag MTJ, the TMR first decreases slightly and then increases, followed by a monotonic decrease. The noncollinear magnetization direction of the CrI3 layers also changes the TMR value of the graphite/n-layer CrI3/graphite MTJ relative to the collinear case, a result in agreement with experiments.