Large enhancement of the giant magnetoresistance in inhomogeneous semiconductors: Dependence on magnetic field direction

In high-mobility Hg1-xCdxTe (x=0.10), the physical giant magnetoresistance (GMR), due to the orbital motion of the carriers in the applied magnetic fi eld, is apparent at high magnetic field (H > 1/mu e). At low field (H < 1/m u(e)), this is enhanced by a geometrical GMR associated with conducting inh omogeneities in the semiconductor. In previous work, we have presented a mo del which accounts quantitatively for the GMR enhancement. Here we report o n the dependence of the GMR on the direction of the magnetic field. The tra nsverse GMR shows the low-field boost expected; in the longitudinal case bo th the physical and the geometrical MR are expected to vanish, and indeed t he measured longitudinal GMR is very small. (C) 1999 American Institute of Physics. [S0021-8979(99)26308-6].