High-Performance <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:msub><mml:mi>Fe</mml:mi><mml:mi>x</mml:mi></mml:msub><mml:msub><mml:mrow><mml:mi>Ge</mml:mi><mml:mi>Te</mml:mi></mml:mrow><mml:mn>2</mml:mn></mml:msub><mml:mstyle displaystyle="false" scriptlevel="0"><mml:mtext>−</mml:mtext></mml:mstyle></mml:math>Based (<i>x</i> =<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:mspace width="0.1em"/></mml:math>4 or 5) van der Waals Magnetic Tunnel Junctions
Baochun Wu, Shibo Fang, Jie Yang, Shiqi Liu, Yuxuan Peng, Qiuhui Li, Zhongchong Lin, Junjie Shi, Wenyun Yang, Zhaochu Luo, Changsheng Wang, Jinbo Yang, Jing Lü, Honglin Du
Abstract
Recently synthesized two-dimensional (2D) van der Waals (vdW) ferromagnets, ${\mathrm{Fe}}_{x}{\mathrm{Ge}\mathrm{Te}}_{2}$ (x = 4 and 5), have attracted great attention due to their room-temperature Curie temperature. By using ab initio noncollinear-spin quantum transport simulations, we predict a monotonic increasing tendency of the tunneling magnetoresistance (TMR) with increasing \ensuremath{\theta} (the angle between the spins of the two electrodes) in ${\mathrm{Fe}}_{x}{\mathrm{Ge}\mathrm{Te}}_{2}$/graphene/${\mathrm{Fe}}_{x}{\mathrm{Ge}\mathrm{Te}}_{2}$ vdW magnetic tunnel junctions (MTJs). The calculated maximal TMR of the two MTJs is up to 7000% and 1100% for x = 4 and 5, respectively, and the former is even nearly 6 times larger than that of the commonly used $\mathrm{Mg}\mathrm{O}$-based MTJ (1000% at 5 K) owing to nearly perfect spin polarization. The calculated maximal spin-transfer torque per voltage is 1--2 orders of magnitude larger than that of the $\mathrm{Mg}\mathrm{O}$-based one, resulting in a reduction in the critical current for magnetization reversal by a factor of 4--5. Such high-performance 2D ${\mathrm{Fe}}_{x}{\mathrm{Ge}\mathrm{Te}}_{2}$-based (x = 4 and 5) MTJs are promising for next-generation room-temperature nonvolatile memories.