Fig. 1: Electrical polarization of the nuclear spin of a Cu atom on MgO. | Nature Nanotechnology

Fig. 1: Electrical polarization of the nuclear spin of a Cu atom on MgO.

From: Electrically controlled nuclear polarization of individual atoms

Fig. 1

a, Schematic of the experimental set-up that consists of an STM with an ESR capability, and an STM image of Cu atoms (yellow protrusions) on a MgO bilayer on Ag(001) (set point: VDC = 50 mV, IDC = 20 pA). An in-plane magnetic field (B) is applied to set the electron Zeeman energy of Cu. Both VDC and radiofrequency (VRF) voltages are applied to the STM junction to perform ESR. The tip apex is labelled by a black arrow to indicate that the tip is spin polarized. b, Mechanism of the nuclear spin polarization for the coupled electron (S= 1/2) and nuclear (I= 3/2) spin system. The tunnelling electron changes the orientation of the Cu electron spin (dashed orange arrows) by an exchange interaction (orange wavy line), and angular momentum is subsequently transferred from the Cu electron to the Cu nucleus (dashed grey arrows) by the flip-flop hyperfine interaction (grey wavy line).