Origin of linear magnetoresistance in polycrystalline Bi films.

The linear magnetoresistance (LMR) effect is an interesting topic due to its potential practical applications in magnetoelectronic sensors and magnetic random-access memories. We report the LMR in polycrystalline Bi thin films synthesized by the molecular beam epitaxy method. Though the present films are complex and disordered, semimetal to semiconductor transition is observed due to the quantum size effect. The LMR of the topologically protected surface state dominated two-dimensional transport can be mainly described by the theory of mobility fluctuation based on the Parish-Littlewood (PL) model. In addition, when the temperature is below 10 K, the LMR is originated from the linear energy dispersion based on the quantum model as the supplement of the PL model. The combination of the quantum and PL model may shed light on the LMR essence of polycrystalline Bi films. [ABSTRACT FROM AUTHOR]