Narrow-Band Semiconductor Heterostructures for Efficient Spintronic Memory Device Applications

We report a new III-V/II-VI semiconductor-based heterostructure system, InSb/CdTe, for low-power spintronic memory device applications. Owning to the strong built-in electric field at the lattice-matched hetero-interface, the giant Rashba spin-orbit coupling with the highly-tunable coefficient ($\alpha_{\mathrm{R}}=0.4\sim 0.7\ \text{eV}\cdot \unicode{x00C5}$) is induced to polarize the spin current. Moreover, the spin-orbit torque (SOT) efficiency of the InSb/CdTe system ($\xi_{\text{SOT}}\sim 1$) is found to be three times larger than conventional heavy-metal materials, which in turn enables the energy-efficient SOT-driven magnetization switching with an ultra-low threshold current density of $4\times 10^{9}\mathrm{A}/\mathrm{m}^{2}$ at room temperature.