Time-resolved measurement of the nuclear spin state with ESR-STM*

Electron Spin Resonance combined with Scanning Tunneling Microscopy (ESR-STM) has emerged as a promising platform for quantum coherent sensing at the nanoscale. However this application has been limited by the short coherence times of electron spins on metallic surfaces.

Nuclear spins on such surfaces might potentially have longer coherence time than electronic spins because they are protected from the two main sources of decoherence in ESR-STM: a small g-factor lowers the effect of magnetic field fluctuations from a vibrating STM tip and nuclear spins have no direct coupling to the electron bath of the metallic environment.

To uncover this potential, we investigate a nuclear spin of ⁴⁹Ti on MgO/Ag. In this system the nuclear spin state population has been shown to be accessible to ESR-STM already through the hyperfine interaction. Furthermore, recent research on this system found efficient nuclear spin pumping by electron scattering with the ⁴⁹Ti placed on the oxygen site of the MgO surface, polarising the nuclear spin to an excited state.

We explore various time-resolved measurement techniques to find yet unknow properties of this nuclear spin, like the relaxation time.