IMPROVED WEAK-FIELD MAGNETORESISTANCE ANALYSIS FOR (001)-ORIENTED THIN-FILMS AND SURFACE-LAYERS WITH CUBIC OR TETRAGONAL SYMMETRY

Weak-field magnetoresistance (WFMR) behavior is described for (001) -oriented films and surface layers in which the sample current lies along a nonspecial direction in the plane. It is shown that four independent WFMR measurements may be made on one sample in this configuration. For cubic crystals, this permits the Seitz-Pearson-Suhl WFMR coefficients b, c, and d to be determined and to be checked for internal consistency. If for any reason, the symmetry of the environment becomes tetragonal (that is, the symmetry axis normal to the film plane becomes distinguishable from the in-plane symmetry axes), then the four coefficients b, b′, c, and d appropriate for this case may be obtained. In either event, the data are more convenient to measure and are more reliable since they are extracted from a single sample. This new approach seems potentially useful as a sensitive indicator of electronic anisotropy over a broad range of environments, including cubically symmetric transport at one extreme and quantized two-dimensional conductivity at the other.