Magnetothermoelectric power in Co/Pt layered structures: Interface versus bulk contributions

Frauen, Axel; Kobs, A.; Böhnert, Tim; Michel, Ann-Kathrin; Winkler, G.; Nielsch, Kornelius; Oepen, Hans Peter

doi:10.1103/physrevb.92.140402

Cited by 7 publications

(5 citation statements)

References 43 publications

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“…Nevertheless microscopic models can be built, such as Mott's formula that account for the measured α [23]. This approach delivered good agreement with experimental results relating α to the electronic transport and magneto transport properties of some materials (see [24] and references therein).…”

Section: Evaluation Of the Electronic Entropymentioning

confidence: 80%

Electronic entropy change in Ni-doped FeRh

Pérez

Chirkova

Skokov

et al. 2019

Materials Today Physics

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The net entropy change corresponding to the charge carriers in a Ni-doped FeRh bulk polycrystal was experimentally evaluated in a single sample using low temperature heat capacity experiments with applied magnetic field, and using Seebeck effect and Hall coefficient measurements at high temperatures across the first order transition. From the heat capacity data a value for the electronic entropy change ∆S el ≈ 8.9 J kg −1 K −1 was extracted, whereas a value of up to 4 J kg −1 K −1 was obtained form the Seebeck coefficient. Additionally, the analysis of the Seebeck coefficient allows tracing the evolution of the electronic entropy change with applied magnetic field. An increase of the electronic entropy with increasing applied magnetic field is evidenced, as high as 10 percent at 6 T.

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Section: Evaluation Of the Electronic Entropymentioning

confidence: 80%

Electronic entropy change in Ni-doped FeRh

Pérez

Chirkova

Skokov

et al. 2019

Materials Today Physics

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“…In current-in-plane geometry, the longitudinal resistivity of all-metallic layered structures, such as Co/Pt and Co/Pd, depends on the orientation of M with respect to the interface as a consequence of the anisotropic interface MR (AIMR) [15][16][17][18][19][20][21][22]. For such systems the inelastic-scattering probability at the interfaces is largest for M oriented parallel to the film normal [polar geometry, see Fig.…”

Section: Introductionmentioning

confidence: 99%

Disentangling interface and bulk contributions to the anisotropic magnetoresistance in Pt/Co/Pt sandwiches

Kobs

Oepen

2016

Phys. Rev. B

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We report on interfacial contributions to the anisotropic magnetoresistance (AMR) in Co layers sandwiched between Pt. Utilizing the Fuchs-Sondheimer formalism interface contributions can be separated from bulklike AMR. We demonstrate that for all-metal systems interfacial AMR is also present when varying the magnetization within the film plane. This interfacial in-plane AMR is two times smaller than the contribution that arises when the magnetization is varied within the plane perpendicular to the current direction. This finding is in contrast to the spin Hall MR found for ferromagnetic insulator/Pt bilayers revealing the existence of different MR effects at the interfaces of Pt with conducting and insulating ferromagnets.

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“…A transverse Mott relation between the ANE and the AHE has been described theoretically and proven for dilute magnetic semiconductors [47,48], but the relation for planar transverse effects has not been explored or demonstrated to our knowledge. Our group and others have previously shown that the Mott relation can be demonstrated in metallic FM samples by changing the values of ρ and α via applied magnetic fields at a fixed T [45,49,50]. These experiments have been interpreted by some as a demonstration that the energy derivative of ρ in equation ( 1) is independent of field, and can be used to determine a numerical value for this derivative.…”

Section: Introductionmentioning

confidence: 91%

Relation of planar Hall and planar Nernst effects in thin film permalloy

Wesenberg¹,

Hojem²,

Bennet³

et al. 2018

J. Phys. D: Appl. Phys.

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We present measurements of the planar Nernst effect (PNE) and the planar Hall effect (PHE) of nickel-iron (Ni-Fe) alloy thin films. We suspend the thin-film samples, measurement leads, and lithographically-defined heaters and thermometers on silicon-nitride membranes to greatly simplify control and measurement of thermal gradients essential to quantitative determination of magnetothermoelectric effects. Since these thermal isolation structures allow measurements of longitudinal thermopower, or the Seebeck coefficient, and four-wire electrical resistivity of the same thin film, we can quantitatively demonstrate the link between the longitudinal and transverse effects as a function of applied in-plane field and angle. Finite element thermal analysis of this essentially 2D structure allows more confident determination of the thermal gradient, which is reduced from the simplest assumptions due to the particular geometry of the membranes, which are more than 350 μm wide in order to maximize sensitivity to transverse thermoelectric effects. The resulting maximum values of the PNE and PHE coefficients for the Ni-Fe film with 80% Ni we study here are α PNE,max = 30 nV K −1 and ρ PHE,max = 2 nΩ m, respectively. All signals are exclusively sin 2θ symmetry with applied field, ruling out longdistance spin transport effects. We also consider a Mott-like relation between the PNE and PHE, and use both this and the standard Mott relation to determine the energy-derivative of the resistivity at the Fermi energy to be ∂ρ/∂E = 4.7 × 10 −7 Ω m eV −1 , which is very similar to values for films we previously measured using similar thermal platforms. Finally, using an estimated value for the lead contribution to the longitudinal thermopower, we show that the anisotropic magnetoresistance (AMR) ratio in this Ni-Fe film is two times larger than the magnetothermopower ratio, which is the first evidence of a deviation from strict adherence to the Mott relation between Seebeck coefficient and resistivity.

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Magnetothermoelectric power in Co/Pt layered structures: Interface versus bulk contributions

Cited by 7 publications

References 43 publications

Electronic entropy change in Ni-doped FeRh

Electronic entropy change in Ni-doped FeRh

Disentangling interface and bulk contributions to the anisotropic magnetoresistance in Pt/Co/Pt sandwiches

Relation of planar Hall and planar Nernst effects in thin film permalloy

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