Negative Magnetoresistance Generated by Combination of Spin--Orbit Interaction and Applied Magnetic Field
We have theoretically studied a negative magnetoresistance (MR) the mechanism of which is completely different from conventional mechanisms, i.e., spin-related mobility-increased mechanisms and orbital-motion-related mechanisms including a quantum interference effect. Our proposed negative MR is cau...
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| Published in: | Japanese Journal of Applied Physics Vol. 51; no. 2; pp. 023001 - 023001-7 |
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| Main Authors: | , , , , , , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
The Japan Society of Applied Physics
01-02-2012
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| Online Access: | Get full text |
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| Summary: | We have theoretically studied a negative magnetoresistance (MR) the mechanism of which is completely different from conventional mechanisms, i.e., spin-related mobility-increased mechanisms and orbital-motion-related mechanisms including a quantum interference effect. Our proposed negative MR is caused by the interplay between a spin--orbit interaction (SOI) and the Lorentz force due to an externally applied magnetic field. We have phenomenologically approached this mechanism using the Drude-like model, in which the carrier scattering by SOI is considered as a transverse scattering term in addition to the longitudinal scattering term due to usual collisions and the Lorentz force term. Also, the possibility of observing our proposed negative MR was discussed by comparing our prediction with experimental results for Ni and Gd films, which were newly measured in this study. |
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| Bibliography: | (Color) Schematics of carrier (electron) kinematics under the presence of scattering by SOI in (a) paramagnetic conductors in the absence of $\mathbf{B}$, (b) paramagnetic conductors in the presence of $\mathbf{B}$ stronger than SOI, and (c) perfectly spin-polarized ferromagnetic conductors. SOI-related parameter $S$ is assumed to be a negative value. Assessment of (a) $(\rho_{xx}-\rho_{0})/\rho_{0}$ and (c) $\rho_{yx}/\rho_{0}$ as a function of $\mathbf{B}$ using eqs. ( ) and ( ). Calculations are made with $\mu S=0.3$ and the level of spin polarization $P_{\text{s}}$ assumed as in (b). This calculation assumes that both charge type and $S$ value are negative. (Color) Room-temperature Hall resistivities (open circles) measured as a function of magnetic field in (a) Ni and (b) Gd films. The magnetic field is applied to the direction perpendicular to the sample plane. The red and blue lines indicate calculations using eq. ( ) with parameters listed in Table . Room-temperature magnetizations (open circles) measured as a function of magnetic field in (a) Ni and (b) Gd films. The magnetic field is applied in the direction perpendicular to the sample plane. The solid lines indicate calculations using the Brillouin function. Room-temperature transverse magnetoresistivities measured as a function of magnetic field in (a) Ni and (b) Gd films. The magnetic field is applied in the direction perpendicular to the sample plane. The solid lines indicate calculations using eq. ( ) with parameters listed in Table . Hall resistivity and transverse magnetoresistivity calculated as a function of magnetic field using eqs. ( ) and ( ). The calculations are made with electron mobilities of $-1.8 \times 10^{-5}$ m 2 V -1 s -1 (dashed line) and $-1.8 \times 10^{-3}$ m 2 V -1 s -1 (solid line). |
| ISSN: | 0021-4922 1347-4065 |
| DOI: | 10.1143/JJAP.51.023001 |