Coherent manipulation of nuclear spins using spin injection from a half-metallic spin source

We have developed a nuclear magnetic resonance (NMR) system that uses spin injection from a highly polarized spin source. Efficient spin injection into GaAs from a half-metallic spin source of Mn-rich $\mathrm{C}{\mathrm{o}}_{2}\mathrm{MnSi}$ enabled an efficient dynamic nuclear polarization of Ga and As nuclei in GaAs and a sensitive detection of NMR signals. Moreover, coherent control of nuclear spins, or the Rabi oscillation between two quantum levels formed at Ga nuclei, induced by a pulsed NMR has been demonstrated at a relatively low magnetic field of \ensuremath{\sim}0.1 T. This provides a novel all-electrical solid-state NMR system with the high spatial resolution and high sensitivity needed to implement scalable nuclear-spin-based qubits.