Current-induced control of the electron-nuclear spin system in semiconductors on a micrometer scale

The ability of using onchip microcoils to control the electron–nuclear spin system in semiconductors is demonstrated. Electrically generated magnetic fields of several tens of mT can be obtained on a micrometer length scale, which are switchable on a sub‐ns time scale due to the low complex coil impedance. This allows one to electrically (i) manipulate the nuclear spins by means of nuclear magnetic resonance in n‐GaAs and (ii) control the hyperfine flip‐flop rate in CdSe/ZnSe quantum dots. Microcoils, lithographically defined on top of a semiconductor are utilized for generating local on‐chip magnetic fields. Due to the low coil impedance, switching times on a sub‐nanosecond time scale are achieved allowing an ultrafast electrical manipulation and optical read‐out of the electron‐nuclear spin system.