MAGNETIC-FIELD DEPENDENCE OF HALL RESISTANCE IN THIN-FILMS OF PURE BISMUTH

Hall resistance has been measured in thin films of pure bismuth at 4.2 K in magnetic fields up to about 8 T. Fields were applied parallel to the trigonal axis, which is perpendicular to the plane of the film, and the thicknesses ranged from 30 to 300 nm. In thinner films, the Hall resistance remained in the negative region. In films of intermediate thickness, as the field increased the Hall resistance first decreased, reaching a Minimum in the negative region, then increased to enter the positive region at higher fields. For thicker films, except in a narrow range of low fields, the Hall resistance was positive and increased in magnitude with the field. Superimposed on the general trend of the Hall resistance versus magnetic field, Shubnikov-de Haas-type oscillations have also been observed.