Large magnetoresistance in postannealed Bi thin films

Abstract

We have observed a large increase in the magnetoresistance(MR) of molecular beam epitaxygrown Bi thin films, which were subjected to a postannealing procedure 3 ° C below the Bi melting point. We have achieved an increase in the MR by a factor of 2560 at helium temperatures compared with of 343 for an as-grown film. The enhancement of the MR in the annealed films is due to higher electron and hole mobilities (μ e ≈1×10 6 cm 2 / V s at 5 K) relative to those of the as-grown films (μ e ≈9×10 4 cm 2 / V s at 5 K). The enhancement of the mobility in the annealed films is also supported by the observation of Shubnikov–de Haas oscillations.