Spin-dependent Peltier effect of perpendicular currents in multilayered nanowires

Gravier, L.; Serrano-Guisan, S.; Reuse, F.; Ansermet, Jean-Philippe

doi:10.1103/physrevb.73.052410

Cited by 128 publications

(35 citation statements)

References 18 publications

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“…The connection between these two important fields has been established in studies of thermoelectric properties of magnetic nanostructures. [1][2][3][4][5][6][7][8][9][10] This interplay between heat and spin transport, now referred to as spin caloritronics, 9,11 has recently gained impetus because the combination of thermoelectrics and spintronics offers unique possibilities. On the one hand, it provides a new, spin-based approach to thermoelectric power generation and cooling.…”

Section: Introductionmentioning

confidence: 99%

Thermal spin current and magnetothermopower by Seebeck spin tunneling

et al. 2012

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The recently observed Seebeck spin tunneling, the thermoelectric analog of spin-polarized tunneling, is described. The fundamental origin is the spin dependence of the Seebeck coefficient of a tunnel junction with at least one ferromagnetic electrode. Seebeck spin tunneling creates a thermal flow of spin-angular momentum across a tunnel barrier without a charge tunnel current. In ferromagnet/insulator/semiconductor tunnel junctions this can be used to induce a spin accumulation (\Delta \mu) in the semiconductor in response to a temperature difference (\Delta T) between the electrodes. A phenomenological framework is presented to describe the thermal spin transport in terms of parameters that can be obtained from experiment or theory. Key ingredients are a spin-polarized thermoelectric tunnel conductance and a tunnel spin polarization with non-zero energy derivative, resulting in different Seebeck tunnel coefficients for majority and minority spin electrons. We evaluate the thermal spin current, the induced spin accumulation and \Delta\mu/\Delta T, discuss limiting regimes, and compare thermal and electrical flow of spin across a tunnel barrier. A salient feature is that the thermally-induced spin accumulation is maximal for smaller tunnel resistance, in contrast to the electrically-induced spin accumulation that suffers from the impedance mismatch between a ferromagnetic metal and a semiconductor. The thermally-induced spin accumulation produces an additional thermovoltage proportional to \Delta\mu, which can significantly enhance the conventional charge thermopower. Owing to the Hanle effect, the thermopower can also be manipulated with a magnetic field, producing a Hanle magnetothermopower.Comment: 10 pages, 3 figures, 1 tabl

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Section: Introductionmentioning

confidence: 99%

Thermal spin current and magnetothermopower by Seebeck spin tunneling

et al. 2012

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“…The spin-mixing mechanism suggested here is effective only for small cluster systems, for which the current flows through the magnetic cobalt grains; for larger clusters, the current flow in the Cu matrix dominates and the MTGV vanishes. The prospects for room-temperature application are favourable, MTGV at room temperature has already been observed in nanowires 17 . A detailed analysis of transport in multilayers with the current perpendicular to the interfaces was carried out and suggests that the right elemental combination is critical.…”

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confidence: 99%

“…The mean sizes of the embedded clusters used in this study were n = 15;600;2,300 and 6,500 atoms per cluster. Besides conventional resistance measurements, we carried out a thermoelectric experiment that measures the thermogalvanic voltage (TGV) and that was initially developed for multilayer systems 14,17 . The principle of this experiment is shown in Fig.…”

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confidence: 99%

Enhanced magnetic field sensitivity of spin-dependent transport in cluster-assembled metallic nanostructures

et al. 2006

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The emerging field of spintronics explores the many possibilities offered by the prospect of using the spin of the electrons for fast, nanosized electronic devices. The effect of magnetization acting on a current is the essence of giant or tunnel magnetoresistance. Although such spintronics effects already find technological applications, much of the underlying physics remains to be explored. The aim of this article is to demonstrate the importance of spin mixing in metallic nanostructures. Here we show that magnetic clusters embedded in a metallic matrix exhibit a giant magnetic response of more than 500% at low temperature, using a recently developed thermoelectric measurement. This method eliminates the dominating resistivity component of the magnetic response and thus reveals an intrinsic spin-dependent process: the conduction-electron spin precession about the exchange field as the electron crosses the clusters, giving rise to a spin-mixing mechanism with strong field dependence. This effect appears sensibly only in the smallest clusters, that is, at the level of less than 100 atoms per cluster. Spintronics seeks to exploit the interplay of spin-polarized conduction electrons and magnetization in nanostructures. Spin-dependent scattering leads to giant magnetoresistance [1][2][3][4][5] (GMR) and tunnelling magnetoresistance [6][7][8] , whereas the converse effect of a spin-polarized current on the magnetization 9-11 can be taken advantage of in magnetoresistive memory bits 12 and gigahertz oscillators 13 . GMR as a field sensing measurement of a resistivity ratio R/R is dominated by non-magnetic and spin-independent scattering processes determining R. Instead, the thermoelectric measurement protocol developed in our laboratory 14 depends on the first derivative of R with respect to the temperature and thus suppresses this resistive contribution. This allows us to fully reveal the otherwise negligible spin-mixing processes. In multilayers this mechanism is essentially a spin-dependent Peltier effect that roughly doubles the field sensitivity compared with GMR 14 . Here we have applied this measurement protocol to granular clusterassembled materials 15 , the geometry of which is not appropriate for a Peltier effect. Hence a clearly different microscopic mechanism takes a predominant role here. We invoke the predominance of spin mixing caused by a spin-precession effect 16 that is completely different in nature. Spin mixing was predicted to decrease GMR responses, as it scrambles the two spin channels of conduction. In our measurement scheme, on the contrary, it results in a 100-fold increase of the field response compared with GMR. The combined use of cluster-assembled materials and a novel measurement method thus reveal a different spin transport effect and may open a new route towards possible applications.Samples were prepared (see the 'Methods' section) according to the strategy of 'cluster-assembled materials' (Fig. 1). Briefly, the samples consist of thin films of copper in which well-defined cobalt clu...

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“…4 Moreover, the discovery of spin-dependent thermal effects, 5,6 e.g. the spin-Seebeck effect, 7 thermal spin injection, 8 and, very recently, the spin-dependent Peltier effect 9,10 has stimulated the interest in small scale heat flow control. Local temperature control and detection are crucial in the experimental study of these effects.…”

Section: Introductionmentioning

confidence: 99%

Nanoscale temperature sensing using the Seebeck effect

Bakker¹,

Flipse²,

Wees³

2012

Journal of Applied Physics

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Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. Download date: 12-05-2018Nanoscale temperature sensing using the Seebeck effect We experimentally study the effect of Joule heating on the electron temperature in metallic nanoscale devices and compare the results with a diffusive 3D finite element model. The temperature is probed using four thermocouples located at different distances from the heater. A good quantitative agreement, within 30%, between the experimental data and the modeling is obtained. Since we observe a strong thickness dependence of the electrical conductivity of our metals, we find that the Joule heating in nanoscale devices is often incorrectly calculated if bulk conductivities are used. Furthermore, Peltier heating=cooling is investigated and the combination with Seebeck temperature measurements provides us with a method to determine the Seebeck coefficient of a material.

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Spin-dependent Peltier effect of perpendicular currents in multilayered nanowires

Cited by 128 publications

References 18 publications

Thermal spin current and magnetothermopower by Seebeck spin tunneling

Thermal spin current and magnetothermopower by Seebeck spin tunneling

Enhanced magnetic field sensitivity of spin-dependent transport in cluster-assembled metallic nanostructures

Nanoscale temperature sensing using the Seebeck effect

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