Gate switchable spin-orbit splitting in a MoTe2/WTe2 heterostructure from first-principles calculations

Transition-metal dichalcogenides are good candidates for spintronic technologies owing to their giant intrinsic spin-orbit splitting. Manipulation of energy splitting is highly desirable for further practical devices. In this work, we provide a simple route to modulate spin-orbit splitting in van der Waals ${\mathrm{MoTe}}_{2}/{\mathrm{WTe}}_{2}$ heterostructure. By introducing an external electric field pointing from ${\mathrm{MoTe}}_{2}$ to ${\mathrm{WTe}}_{2}$, the spin-orbit splitting of individual layers can be switched more than 10 meV. The spin-orbit splitting of ${\mathrm{MoTe}}_{2}$ switches from 213 meV to $204\ensuremath{\sim}180\phantom{\rule{0.16em}{0ex}}\mathrm{meV}$ under electric field of $0.02\ensuremath{\sim}0.24$ V/\AA{}. The energy splitting of ${\mathrm{WTe}}_{2}$ switches to $490\ensuremath{\sim}513\phantom{\rule{0.16em}{0ex}}\mathrm{meV}$. The underlying physics stems from interlayer charge redistribution and band repulsion, where the parallel spin in the sub-bands plays a role. Our findings provide a clue to actively control the spin-orbit splitting in transition-metal dichalcogenides, which is of great importance for developing innovative nonmagnetic spintronic devices.