Manifestation of the spin-orbit interaction in bismuth films in a parallel magnetic field

The magnetic field dependence of the resistance of bismuth thin films (100-700 A thick) at low temperatures (1.5-77 K) are analyzed in the conceptual framework of quantum corrections to the conductivity due to weak localization and electron interaction effects. It is shown that the diversity and variability of the magnetoresistance curves in a parallel field upon variations of the thickness and temperature are due to the fact that the spin-orbit interaction time tau(so) increases with increasing field, altering the relationship between tau(so) and the phase relaxation time tau(phi). This result supports the hypothesis that the strong spin-orbit interaction manifested in the surface scattering of electrons is due to the existence of a potential gradient near the metal surface, and a parallel magnetic field alters the orientation of the spins, accompanied by a decrease of the rate of spin-orbit processes.