Scaling Behavior of Magnetoresistance with the Layer Number in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:msub><mml:mrow><mml:mi>Cr</mml:mi><mml:mi mathvariant="normal">I</mml:mi></mml:mrow><mml:mn>3</mml:mn></mml:msub></mml:math> Magnetic Tunnel Junctions
Baochun Wu, Jie Yang, Ruge Quhe, Shiqi Liu, Chen Yang, Qiuhui Li, Jiachen Ma, Yuxuan Peng, Shibo Fang, Junjie Shi, Jinbo Yang, Jing Lü, Honglin Du
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 $\mathrm{Ag}/$n-layer ${\mathrm{Cr}\mathrm{I}}_{3}/\mathrm{Ag}$ and graphite/n-layer ${\mathrm{Cr}\mathrm{I}}_{3}$/graphite magnetic tunnel junctions (MTJs) by using ab initio quantum-transport simulations. The calculated monotonic increasing TMR of the graphite/n-layer ${\mathrm{Cr}\mathrm{I}}_{3}$/graphite MTJ with n = 2--4 at zero bias agrees with the experimental value. The TMR of the $\mathrm{Ag}/$n-layer ${\mathrm{Cr}\mathrm{I}}_{3}/\mathrm{Ag}$ MTJ generally increases with the tunnel-barrier layer number, n, that is, from 200% (2-layer ${\mathrm{Cr}\mathrm{I}}_{3}$) to a record ${10}^{9}$% value (12-layer ${\mathrm{Cr}\mathrm{I}}_{3}$) at zero bias but has an odd-even oscillation when n 7. When we apply a bias voltage to the $\mathrm{Ag}/$2-layer ${\mathrm{Cr}\mathrm{I}}_{3}/\mathrm{Ag}$ MTJ, the TMR first decreases slightly and then increases, followed by a monotonic decrease. The noncollinear magnetization direction of the ${\mathrm{Cr}\mathrm{I}}_{3}$ layers also changes the TMR value of the graphite/n-layer ${\mathrm{Cr}\mathrm{I}}_{3}$/graphite MTJ relative to the collinear case, a result in agreement with experiments.