Single-atom nuclear magnetic resonance (NMR) using scanning tunneling microscopy*

Nuclear spins are sensitive probes in chemistry and materials science as well as promising candidates for quantum information processing. Manipulating nuclear spins in condensed matter systems is difficult due to the small nuclear magnetic moment, leading to low polarizations, and addressing them individually is particularly challenging. Here, we demonstrate NMR of individual atoms on a surface in a scanning tunneling microscope (STM) [1]. To achieve NMR, we first polarize nuclear spins using spin-polarized tunneling current. By employing the flip-flop hyperfine interaction, the spin angular momentum of tunneling electrons is transferred to the nucleus. The nuclear polarization is controlled by the current, and read out by electron spin resonance [2, 3]. We further use NMR to sense the local magnetic environment of the electron spin of a single atom. The electrical polarization and driving of the nuclear spin states enable the local spin manipulation for nuclear spintronics and detection of the atomic-scale magnetic environment in nanomagnets.
[1] Yang et al., Nat. Nanotechnol. doi:10.1038/s41565-018-0296-7 (2018).
[2] Yang et al., Phys. Rev. Lett. 119, 227206 (2017).
[3] Willke et al., Science 362, 336 (2018).