Study of large magnetoresistance of thin polycrystalline Bi films annealed at critical temperatures

Abstract

AbstractThis paper reports an investigation of the large magnetoresistance (MR) of 0.3–1.5 µm thick polycrystalline Bi films deposited in vacuum on non‐crystalline substrates and annealed at critical temperatures. The occurrence of critical temperatures is associated with intensive growth of crystallites. It is demonstrated that such films consist of large 50–200 µm high‐quality crystallites and exhibit a large transverse MR. At temperatures higher than 77 K the magnitude of the MR can exceed that of epitaxial Bi films. The experimental results are interpreted on the basis of a polycrystalline Bi thin‐film model. The data suggest that in Te‐doped Bi films the MR can be larger than that in pure Bi films. It is found that the grain‐boundary scattering is weak. However, there exist rather isotropic extra carrier scattering channels which reduce the anisotropy of electrical conductivity and MR. The relative importance of this extra scattering changes with temperature. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)