Dynamic nuclear spin polarization by the Edelstein effect at Bi(111) surfaces

The appreciable electron density in the semimetal Bi and the strong spin-orbit interaction of Bi(111) surfaces allow for the spin transfer between a current of electrons in Bi and its nuclei, in the absence of an external magnetic field. Application of a high current density generates a carrier spin polarization by mainly the Edelstein effect at the Bi(111) surface, which then induces dynamic nuclear polarization via the hyperfine interaction. Quantum transport antilocalization measurements in the Bi(111) thin-films grown on mica indicate a suppression of antilocalization by the in-plane Overhauser field from the nuclear polarization, and allow for the quantification of the Overhauser field. Various delay times between the polarization and measurement result in an exponential decay of the Overhauser field, driven by relaxation time T1. The addition of an external magnetic field does not detectably change the observations. Thus, dynamic nuclear polarization can be achieved without external fields, relying only on the effective electronic field created by carrier spin polarization.

Z. Jiang, V. Soghomonian and J. J. Heremans, "Dynamic Nuclear Spin Polarization Induced by the Edelstein Effect at Bi(111) Surfaces", Phys. Rev. Lett. 125, 106802 (2020).