Enhanced magneto-thermoelectric power factor of a 70 nm Ni-nanowire

Mitdank, R.; Handwerg, Martin; Corinna, Steinweg,; Töllner, William; Daub, M.; Nielsch, Kornelius; Fischer, Saskia F.

doi:10.1063/1.4721896

Cited by 33 publications

(29 citation statements)

References 22 publications

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“…The resulting magneto-Seebeck phenomenon has also been observed in the magnetic-field dependence of inorganic thermoelectrics. [36][37][38] Notably, a magneto-Seebeck effect of 22% was reported in a 70 nm Ni-nanowire with a magnetic field strength B of 0.5 T. 37 The major difference between the previous reports and our current work on magneto-Seebeck effect is that the observation was limited to metallic samples. Our work demonstrates that the same effect can be observed in organic material which recently has been recognized as semi-metallic polymer.…”

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confidence: 52%

“…Our work demonstrates that the same effect can be observed in organic material which recently has been recognized as semi-metallic polymer. 39 Therefore, a relationship between magnetoresistance and thermopower S can be described using Mott's formula: S = (π 2 /3e)k 2 B T[∂lnG/∂E], for a conductance change G with band energy E. 37 It needs to be emphasized that this relation is established under the assumption that PEDOT:PSS presents metallic conductivity as previously reported, instead of being a Fermi glass. 39 In this respect, by using a magnetic field, we can change the thermopower by changing the conductance through magneto-resistance effect.…”

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confidence: 99%

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Magneto-Seebeck effect in an ITO/PEDOT:PSS/Au thin-film device

et al. 2016

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This article reports giant magnetic field effects on the Seebeck coefficient by exerting a Lorentz force on charge diffusion based on vertical multi-layer ITO/PEDOT:PSS/Au thin-film devices. The Lorentz force, induced by an external magnetic field, changes the charge transport and consequently generates angular dependent magnetoresistance. The proposed mechanism of the magneto-Seebeck effect is proved by measuring the magnetoresistance at a parallel, 45o and perpendicular angle to the temperature gradient. The gradual change of the magnetoresistance from a parallel to perpendicular angle indicates that the Lorentz force is a key driving force to develop the magneto-Seebeck effect. Therefore, our experimental results demonstrate a magnetic approach to control the thermoelectric properties in organic materials.

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confidence: 99%

Magneto-Seebeck effect in an ITO/PEDOT:PSS/Au thin-film device

et al. 2016

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“…They found that the Wiedemann-Franz law holds in the field-range of GMR even in the presence of weak inelastic scattering. However, despite of this comprehensive data on thermal conductivity and thermoelectricity of GMR materials, neither the magnetic field dependence of the thermoelectric figure of merit -the magneto-ZT -nor the field dependence of the power factor -the magneto-PF - [21] have been addressed so far.…”

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confidence: 99%

“…This leads to the conclusion, that the energy derivative of the resistivity in Mott's equation is independent of the magnetic field. By changing the spin configuration of a multilayer, the thermopower should also be changed, as inferred by different theoretical models [11,13,21]. However, concerning the Lorenz number L, there are two controversial conclusions.…”

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Magnetothermoelectric figure of merit of Co/Cu multilayers

Krzysteczko

Liebing

et al. 2014

Appl. Phys. Lett.

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The switching of the magnetization configurations of giant magnetoresistance multilayer stacks not only changes the electric and thermal conductivities, but also the thermopower. We study the magnetotransport and the magneto-thermoelectric properties of Co/Cu multilayer devices in a lateral thermal gradient. We derive values of the Seebeck coefficient, the thermoelectric figure of merit, and the thermoelectric power factor. The Seebeck coefficient reaches values up to -18 µV/K at room temperature and shows a magnetic field dependence up to 28.6 % upon spin reversal.In combination with thermal conductivity data of the same Co/Cu stack, we find a spin dependence of the thermoelectric figure of merit of up to 65 %. Furthermore, a spin dependence of the power factor of up to 110 % is derived.

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“…Several experiments have been illustrated it and open a new field, the so-called "Spin Caloritronics". Such experiments are for example the Spin-Seebeck Effect (SSE) [2], Spin Peltier effect [3] TEP in multilayer nanowires [4,5] or thermally induced spin torque in nonlocal lateral spin-valves [6]. Recently an equivalent to TMR for thermoelectric transport was observed, the tunnelling magnetothermoelectric power (TMTEP) [7].…”

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confidence: 99%

Anisotropic magnetothermoelectric power of ferromagnetic thin films

Anwar

Lacoste

Aarts

2017

Journal of Magnetism and Magnetic Materials

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In this article, we report the measurements of the magnetothermoelectric power (MTEP) in metallic ferromagnetic thin films of Ni 80 Fe 20 (Permalloy; Py), Co and CrO 2 at temperatures in the range of 100 K to 400 K. In 25 nm thick Py films and 50 nm thick Co films both the anisotropic magnetoresistance (AMR) and MTEP show a relative change in resistance and thermoelectric power (TEP) of the order of 0.2% when the magnetic field is reversed, and in both cases there is no significant change in AMR or MTEP after the saturation field has been reached. Surprisingly, both Py and Co films have opposite MTEP behaviour although both have the same sign for AMR and TEP. The data on half metallic ferromagnet CrO 2 films show a different picture. Films of thickness of 100 nm were grown on TiO 2 and on sapphire. The MTEP behavior at low fields shows peaks similar to the AMR in these films, with variations up to 1%. With increasing field both the MR and the MTEP variations keep growing, with MTEP showing relative changes of 1.5% with the thermal gradient along the b-axis and even 20% with the gradient along the c-axis, with an intermediate value of 3% for the film on sapphire. It appears that the low-field effects are due to the magnetic domain state, and the high-field effects are intrinsic to the electronic structure of CrO 2 and intergarian tunnelling magnetoresistance that contributes to MTEP as tunnelling-MTEP. Our results will stimulate the research work in the field of spin dependent thermal transport in ferromagnetic materials to further develop spin-Caloritronics.

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Enhanced magneto-thermoelectric power factor of a 70 nm Ni-nanowire

Cited by 33 publications

References 22 publications

Magneto-Seebeck effect in an ITO/PEDOT:PSS/Au thin-film device

Magneto-Seebeck effect in an ITO/PEDOT:PSS/Au thin-film device

Magnetothermoelectric figure of merit of Co/Cu multilayers

Anisotropic magnetothermoelectric power of ferromagnetic thin films

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