Magnetoresistance in semimetallic bismuth thin films

The magnetotransport properties of electroplated and sputtered Bi thin films have been investigated in the range 4 - 300 K. A marked increase from 5,200 % to 80,000 % in the ordinary magnetoresistance (MR) for the electroplated Bi thin film was observed after thermal anneal at 4 K. The MR ratios for the as-grown and the annealed Bi thin films were found to be 560 % and 590 %, respectively, at 300 K. On the other hand, the MR for the Bi film grown by sputtering was hardly observed at 4 and 300 K, whereas the MR ratios after annealing were found to reach 30,000 % at 4 K and 600 % at 300 K. The room temperature MR in the sputtered films was found to depend on the trigonal-axis oriented microstructures and grain size, in contrast to the electroplated films. Our results support the view that the grain-boundary scattering mechanism is dominant in the MR response at room temperature, whereas the textured grains oriented to the trigonal axis are dominant in the MR response at 4 K for both electroplated and sputtered samples.