We have carried out magnetotransport measurements of the bipolar conductor YHx () employing the ferromagnetic conductor Co as the source and drain electrodes, from which the spin-polarized currents are injected. Both the Hall resistivity (HR) and transverse magnetoresistivity (TMR) ratio are enhanced by a factor of ∼3 and ∼6, respectively, when Co electrodes are used instead of Au electrodes. We derived two types of closed formulae of HR and TMR, the first (second) type of which was derived by simultaneously (independently) considering the external magnetic field and spin–orbit interaction, but both types of which were derived by considering spin-dependent electrochemical potential caused by the presence of the ferromagnetic electrodes. Carrier parameter assessments based on the two types of formulae as well as the two types of electrode samples enable us to infer that coupling mechanisms between the external magnetic field and spin–orbit interaction are required for the precise interpretation of HR and TMR measured in the simultaneous presence of magnetic field and spin splitting in a diffusion force field, especially for conductors with strong spin–orbit interaction.

We have proposed an enhancement mechanism of the Hall effect, the signal of which is amplified due to the generation of a sustaining mode of spin current. Our analytic derivations of the Hall resistivity revealed the conditions indispensable for the observation of the effect: (i) the presence of the transverse component of an effective electric field due to spin splitting in chemical potential in addition to the longitudinal component; (ii) the simultaneous presence of holes and electrons each having approximately the same characteristics; (iii) spin-polarized current injection from magnetized electrodes; (iv) the boundary condition for the transverse current (J c,y = 0). The model proposed in this study was experimentally verified by using van der Pauw-type Hall devices consisting of the nonmagnetic bipolar conductor YH x (x ' 2) and TbFeCo electrodes. Replacing Au electrodes with TbFeCo electrodes alters the Hall resistivity from the ordinary Hall effect to the anomalous Hall-like effect with an enhancement factor of approximately 50 at 4 T. We interpreted the enhancement phenomenon in terms of the present model.

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