Influence of Point-Like Disorder on the Hall Resistivity Behavior in an Anisotropic Planar Pinning Potential

Abstract

Explicit current- and temperature-dependent expressions for anisotropic longitudinal and transverse nonlinear magnetoresistivities are derived and analyzed on the basis of a Fokker–Planck approach for two-dimensional vortex dynamics in a washboard pinning potential in the presence of point-like disorder. Gradually increasing the strength of the point-like pinning (in an experiment this is simply done by irradiation of the sample with different doses of high-energy electrons) this theory predicts a gradual decrease of the anisotropy of the magnetoresistivities. The physics of the transition from the recently discussed new scaling relations for anisotropic Hall resistivities in the absence of point-like pins to the well-known scaling relations for isotropic pinning is elucidated. This is discussed in terms of a gradual isotropization of the guided vortex motion responsible for the existence in a washboard pinning potential of new anisotropic Hall voltages which are odd with respect to magnetic field reversal.