Giant magnetoresistance enhancement in inhomogeneous semiconductors

We show that the low-field magnetoresistance (MR) of a semiconductor with inhomogeneities which are more conducting than the surrounding matrix is enhanced significantly compared to that of the homogeneous material. The enhancement results from a magnetic field induced geometric effect in which at high field the current is deflected around the conducting inhomogeneity. A model based on previous work by Wolfe et al. has been augmented to include the physical MR. The augmented model is used to account quantitatively for a 50-fold anomalous enhancement of the giant magnetoresistance (GMR) observed at low field in (near) zero-band-gap thin-film Hg1−xCdxTe (x≈0.1). The practical implications of the GMR boost are noted.