High-Performance FexGeTe2− Based ( x = 4 or 5) van der Waals Magnetic Tunnel Junctions

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.