Magnetic Field Effects on Thermopower ofFe/Cr and Cu/Co/Cu/Ni(Fe) Multilayers

Sakurai, J.; Horie, Masahiro; Araki, S.; Yamamoto, H.; Shinjo, Teruya

doi:10.1143/jpsj.60.2522

Cited by 66 publications

(34 citation statements)

References 4 publications

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“…This theoretical prediction is in agreement with experimental observations. 185,186 Tsymbal et al 184 have also shown that their model accounts for the experimentally observed sign of . In figure b the agreement is improved if additional disorder is introduced to the top Cu/Co interface that is attributed to segregation of low surface energy Cu through Co in the experiment.…”

mentioning

confidence: 90%

“…112 The decisive role of the spin-polarized band structure for spin-dependent transport in magnetic layered systems is supported by studying the thermoelectric power (TEP) in Co/Cu and Fe/Cr multilayers Tsymbal et al 184 Experimental studies show that TEP is positive in Fe/Cr magnetic multilayers. 185 The magneto-thermoelectric power (MTEP), i.e. the change in TEP associated with an applied magnetic field, is also positive at room temperature.…”

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confidence: 99%

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Perspectives of giant magnetoresistance

Tsymbal¹,

Pettifor²

2001

Solid State Physics

252

189

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mentioning

confidence: 90%

mentioning

confidence: 99%

Perspectives of giant magnetoresistance

Tsymbal¹,

Pettifor²

2001

Solid State Physics

252

189

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“…if the conductivity asymmetry is not energy dependent. The proportionality between R GM R /R 0 and Σ GM R /(ΛS t ) was observed experimentally [13,15,18,19] and the proportionality factor P GM R = − …”

Section: Out-of-equilibrium Magnetothermopowermentioning

confidence: 69%

“…Magneto-thermoelectric power (MTEP) experiments in GMR structures [13,14,15,16,17,18,19] however point out the need for a deeper understanding of the dissipative mechanism responsible for the giant magnetothermopower related to GMR. The problem of s-d electronic relaxation at the interface was also put forward in the context of current induced magnetization reversal mechanisms in various systems exhibiting AMR [20,21,22,23,24].…”

Section: Introductionmentioning

confidence: 99%

Anisotropic magnetothermopower: Contribution of interband relaxation

et al. 2006

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Spin injection in metallic normal/ferromagnetic junctions is investigated taking into account the anisotropic magnetoresistance occurring in the ferromagnetic layer. On the basis of a generalized two-channel model, it is shown that there is an interface resistance contribution due to anisotropic scattering, besides spin accumulation and giant magnetoresistance. The corresponding expression of the thermoelectric power is derived and compared with the expression accounting for the thermoelectric power produced by the giant magnetoresistance. Measurements of anisotropic magneto-thermoelectric power are presented in electrodeposited Ni nanowires contacted with Ni, Au, and Cu. It is shown that this thermoelectric power is generated at the interfaces of the nanowire. The results of this study indicate that, while the giant magnetoresistance and the corresponding thermoelectric power indicate the role of spin-flip scattering, the observed anisotropic magneto-thermoelectric power might be the fingertint of interband s-d relaxation mechanisms.

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“…Spin valve systems and magnetic multilayers displaying giant magnetoresistance effects also exhibit substantial magnetothermopower [1][2][3][4][5][6] with a strong temperature dependence. In metals, the thermopower S is related to the conductivity of electrons taken at a certain energy, σ(ǫ), by the Mott formula, 7 S = −(π 2 k 2 B T /3e) (∂ ln σ(ǫ)/∂ǫ) ǫF , so that it typically contains a small parameter such as k B T /ǫ F .…”

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Magnetothermopower and magnon-assisted transport in ferromagnetic tunnel junctions

McCann

2002

Applied Physics Letters

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We present a model of the thermopower in a mesoscopic tunnel junction between two ferromagnetic metals based upon magnon-assisted tunneling processes. In our model, the thermopower is generated in the course of thermal equilibration between two baths of magnons, mediated by electrons. We predict a particularly large thermopower effect in the case of a junction between two half-metallic ferromagnets with antiparallel polarizations, SAP ∼ −(kB/e), in contrast to SP ≈ 0 for a parallel configuration.Spin valve systems and magnetic multilayers displaying giant magnetoresistance effects also exhibit substantial magnetothermopower 1-6 with a strong temperature dependence. In metals, the thermopower S is related to the conductivity of electrons taken at a certain energy, σ(ǫ), by the Mott formula,T /3e) (∂ ln σ(ǫ)/∂ǫ) ǫF , so that it typically contains a small parameter such as k B T /ǫ F . Theories of transport in magnetic multilayers with highly transparent interfaces based upon the use of the Mott formula have explained the difference between thermopower in the parallel (P) and anti-parallel (AP) configuration of ferromagnetic layers as due to either the difference in the energy dependence of the density of states for majority and minority spin bands in ferromagnetic layers, 8,9 or a different efficiency of electron-magnon scattering for carriers in opposite spin states.3 In particular, the electronmagnon interaction in a ferromagnetic layer was incorporated to explain the observation 3 of a strong temperature dependence of S(T ) and gave, theoretically, a much larger thermopower in the parallel configuration of multilayers with highly transparent interfaces than in the antiparallel one, S P ≫ S AP .In this paper we investigate a model of the electronmagnon interaction assisted thermopower in a mesoscopic size ferromagnet/insulator/ferromagnet tunnel junction, which yields a different prediction. In the model we study below, the bottle-neck of both charge and heat transport lies in a small-area tunnel contact between ferromagnetic metals held at different temperatures, T ± ∆T /2. The thermopower is generated in the course of thermal equilibration between two baths of magnons, mediated by electrons. We find that the magnetothermopower effect is most pronounced in the case of half-metallic ferromagnets, where the exchange spin splitting ∆ between the majority and minority conduction bands is greater than the Fermi energy ǫ F measured from the bottom of the majority band, and the Fermi density of states in the minority band is zero. In a highly resistive antiparallel configuration of such a junction, where the emission/absorption of a magnon would lift the spin-blockade of electronic transfer between ferromagnetic metals, we predict a large thermopower effect, whereas in the lower-resistance parallel configuration thermopower appears to be relatively weak:We also found that for a junction between two conventional ferromagnetic metals, the ability of electronic transfer assisted by magnon emission/absorption to create th...

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Magnetic Field Effects on Thermopower ofFe/Cr and Cu/Co/Cu/Ni(Fe) Multilayers

Cited by 66 publications

References 4 publications

Perspectives of giant magnetoresistance

Perspectives of giant magnetoresistance

Anisotropic magnetothermopower: Contribution of interband relaxation

Magnetothermopower and magnon-assisted transport in ferromagnetic tunnel junctions

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