Abstract
Binary surface alloy made of heavy elements, Pb and Au, has exhibited strong Rashba effect in its band structure. To investigate its corresponding performance in electric transport, we first grew such a PbAu-alloy thin film, composed of the Pb film with PbAu alloy layer on the top, in the UHV chamber. After the sample of PbAu-alloy film was made, we took the sample out of UHV chamber and fabricate it into a Hall-bar device via lithography for low-temperature magneto-resistance measurement with the applied magnetic field parallel to the sample surface. Based on the experimental result, we could find that once the temperature dropped below transition temperature. ~ 6 K, of Pb, the spin-polarized charge current appeared in the transverse direction causing the observed abrupt increase of the voltage. Furthermore, we also observed that the oscillation of voltage as a function of applied magnetic field in the weak limits from 0.2 Tesla to 3.6 Tesla and the non-ohmic behavior in terms of the I-V relation. One can realize the appearance of spin-polarized charge current by considering the influence from Rashba effect, leading to spin Hall or anomalous Hall effect. Such spin -polarized charge current is closely related to superconductivity of Pb thin films; when the temperature goes below the transition temperature, the transport currents would concentrate on the Pb film so as to increase the probability of scattering to top PbAu alloy layer that has giant Rashba effect. Such strong spin-orbital interaction would not just lead to the diffusion of spin-polarized current in transverse direction but very likely breaking time-resolved symmetry via the change of superconducting state under Rashba interaction. When the temperature goes above transition temperature, spin polarized charge current is small, so the behavior becomes more Ohmic. Finally, the measured oscillation of voltage under the weak magnetic field could be realized by considering spin-magnetic moment of electrons in the spin-polarized charged currents exposed to the external magnetic field resulting in precession of spin magnetic moment.