Magnetoresistance Generated by Combination of Spin--Orbit Interaction and Applied Magnetic Field in Bipolar Conductors

We have theoretically studied the magnetotransport properties in bipolar conductors under consideration of the simultaneous presence of an external magnetic field, left--right asymmetric carrier scattering due to spin--orbit interactions, and spin-polarized holes/electrons, predicting both positive and negative transverse magnetoresistance (TMR) terms, the mechanisms of which are completely different from the conventional mechanism in bipolar conductors. The positive TMR term is predicted only for the asymmetric carrier scattering case, the sign of which is the same (negative) between a hole and an electron. The other case of asymmetric scattering, the sign of which is opposite between a hole and an electron, was also determined to always show a negative TMR. Our proposed TMR was experimentally evidenced from the magnetotransport and magnetization measurements of a compensated metal, YH 2 . Also, application to logic gates is discussed on the basis of our proposed mechanism.