Current-induced nuclear spin polarization effects in Bi(111) film flakes with strong spin-orbit interaction

The influence on quantum transport of nuclear spin polarization, induced by hyperfine interactions and the Edelstein effect, was investigated in individual micrometer-size 40 nm thick Bi(111) film flakes. The flakes were obtained by exfoliation and PDMS stamping from epitaxial Bi(111)-on-mica films. The growth method will be discussed. AFM and SEM micrographs of the Bi(111) film clearly show micrometer-size triangular structured islands with 0.4 nm step height (Bi(111) bilayer height). At low temperatures a high current density is applied to generate nonequilibrium carrier spin polarization by the Edelstein effect, which then induces nuclear polarization by hyperfine interactions and dynamic nuclear polarization. The low-temperature quantum transport measurements are carried out both before and after the current application. The quantum phase coherence time and the spin-orbit scattering time are obtained by fitting of weak-antilocalization magnetotransport data. In our Bi(111), the phase coherence time and the spin-orbit scattering time show a dependence on the nuclear spin polarization obtained by hyperfine interactions with the spin-polarized carriers, in turn obtained by the Edelstein effect.