Hall resistivity and transverse magnetoresistivity generated in simultaneous presence of spin-polarized current and external magnetic field in a nonmagnetic bipolar conductor YH₂

Abstract

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.

Resonant Hall effect under generation of a self-sustaining mode of spin current in nonmagnetic bipolar conductors with identical characters between holes and electrons

“…The result is completely different from that observed in the Au electrode Hall device with the same dimensions as the present device. The Au electrode device shows an ordinary Hall effect with a quite small R H of less than 5.0 × 10 −12 m 3 =C, 24) while the TFC=YH 2 Hall device shows an anomalous Hall-like effect with a saturation level of approximately 5 × 10 −10 Ω m. The present result is also different from that observed in the Co electrode device investigated in Ref. 24.…”

“…We called this the BS coupling. 24) The BS coupling is also predicted in an SCC as shown in Eq. (B•2) of Appendix.…”

“…This character is completely different from the calculation made without considering ΔE y because it shows a value of exactly zero if Φ = 0. 24) The mechanism generating nonzero ρ yx at Φ = 0 is related to the generation of the self-sustaining mode of spin current as elucidated in the next subsection.…”

“…Having obtained analytic expressions for ρ yx , we will move to the numerical estimation of their magnitudes. For all assessments including Φ = 0 and Φ ≠ 0 cases with type I and II calculations, we use the carrier parameters determined in our previous study employing Au electrodes-YH 2 channel Hall devices with the same dimensions as the present Hall device: Φ = 0.2%, n h + n e = 6.5 × 10 27 m −3 , μ = 4.9 × 10 −3 m 2 V −1 s −1 , and S = 339 T. 24) The carrier spin polarization P generated by the Pauli paramagnetism was determined experimentally as 21) gs…”

“…The effects of the Ti underlayer and Pd cover layer on the Hall effects of YH 2 were investigated in our previous study using Au electrodes, in which no serious effect of these layers on the Hall effect of YH 2 was observed. 24) The measurements of ρ xx and ρ yx require the potential difference between contacts 2 and 4, V 24 , to occur as a result of the current flow from contacts 1 to 3, and that between 1 and 3, V 13 , to occur as a result of the current flow from contacts 2 to 4, so that ρ xx and ρ yx are obtained respectively from 32)…”