Electric field tuning of spin-orbit coupling in KTaO3 field-effect transistors

We report on the observation of weak antilocalization associated with large spin-orbit coupling in a tunable d electron system: a quasi-two-dimensional electron gas formed in a KTaO3 field-effect transistor. We find that spin-precession length of electrons can be tuned by gate voltage V-G and is as short as tens of nanometers at large V-G. Our results show that 5d transition-metal compounds having strong atomic spin-orbit couplings induced by heavy 5d elements could be utilized to electrically manipulate spins in nanoscale spintronic devices.