Ueber die electromotorischen Kräfte, welche durch den Magnetismus in von einem Wärmestrome durchflossenen Metallplatten geweckt werden

Nernst, W.

doi:10.1002/andp.18872670815

Cited by 85 publications

(51 citation statements)

References 3 publications

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“…The maximum temperature is found at the top owing to the fact the heat dissipation is faster through the bottom substrate than through the top ambient air. A temperature gradient in the z direction will generate an electric current in the same direction, which interacts with the FM layer through the anomalous Hall effect and generates an electric field (∝ ∆T × M sat ) in x direction 10 . This will cause a resistance change in x direction and possesses the same symmetry as that of the USMR.…”

Section: (B)mentioning

confidence: 99%

Thickness dependence of unidirectional spin-Hall magnetoresistance in metallic bilayers

Yin

Han

Jong

et al. 2017

Applied Physics Letters

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A nonlinear magnetoresistance -called unidirectional spin-Hall magnetoresistance -is recently experimentally discovered in metallic bilayers consisting of a heavy metal and a ferromagnetic metal. To study the fundamental mechanism of the USMR, both ferromagnetic and heavy metallic layer thickness dependence of the USMR are presented in a Pt/Co/AlOx trilayer at room temperature. To avoid ambiguities, second harmonic Hall measurements are used for separating spin-Hall and thermal contributions to the non-linear magnetoresistance. The experimental results are fitted by using a drift-diffusion theory, with parameters extracted from an analysis of longitudinal resistivity of the Co layer within the framework of the FuchsSondheimer model. A good agreement with the theory is found, demonstrating that the USMR is governed by both the spin-Hall effect in the heavy metallic layer and the metallic diffusion process in the ferromagnetic layer.In the field of Spintronics, a new way of spin control based on the spin-Hall effect recently has attracted a great deal of attention. It originates from the spinorbit (SO) interaction which converts a charge current into a net flow of spin angular momentum, exerting a SO torque on the magnetization. This leads to an energy-efficient way of writing information to magnetic memories by switching a magnetic entity via sending a charge current through a nearby nonmagnetic metal 1,2 . Apart from writing, a possible way of reading the memory could be achieved by measuring a so-called spin-Hall magnetoresistance (SMR) 3,4 , i.e., a change in electrical resistance due to the spin Hall effect when the spin-accumulation is perpendicular or parallel to the magnetization. Although SMR provides a promising way towards reading memory devices using a twoterminal architecture, the fact that it can only distinguish between the perpendicular and parallel states limits its application.Very recently, a unidirectional contribution to magnetoresistance -called unidirectional spin-Hall magnetoresistance (USMR) -has been reported in a ferromagnetic/heavy metallic (FM/HM) bilayer structure 5-7 . Being different from the ordinary SMR, the resistance changes by reversing the magnetization or the current direction, which could be potentially utilized for reading operation. Based on a drift-diffusion-relaxation theory 8 , this nonlinear behavior is attributed to the dependence of electron mobility on spin-polarization, which is tuned by the spin-Hall effect induced spin accumulation. This spin accumulation is limited to a thin region at the FM/HM interface due to a finite spin diffusion length in both layers, leading to a non-trivial FM and HM thickness dependence of the USMR. So far, this a) E-mail: y.yin@tue.nl particular dependence on thickness is not evidenced by any experiments. Thus, a systematic investigation of how USMR depends on the layer thickness is urgently needed not only for a better understanding of the origin of USMR, but also for the enhancement of USMR in practical applications.In this paper, we...

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Section: (B)mentioning

confidence: 99%

Thickness dependence of unidirectional spin-Hall magnetoresistance in metallic bilayers

Yin

Han

Jong

et al. 2017

Applied Physics Letters

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“…The relevant interface property that determines the spin current transport thereby is the spin mixing conductance. Nevertheless, there has been an ongoing debate regarding the physical origin of the measurement data acquired in spin Seebeck and SMR experiments due to possible contamination with anomalous Nernst effect [19][20][21] or anisotropic magnetoresistance [22,23] caused by static proximity polarization of the normal metal [23]. To settle this issue, a rigorous check of the consistency of the spin-current based physical models across all three effects is needed.…”

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confidence: 99%

Experimental Test of the Spin Mixing Interface Conductivity Concept

et al. 2013

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We perform a quantitative, comparative study of the spin pumping, spin Seebeck and spin Hall magnetoresistance effects, all detected via the inverse spin Hall effect in a series of over 20 yttrium iron garnet/Pt samples. Our experimental results fully support present, exclusively spin currentbased, theoretical models using a single set of plausible parameters for spin mixing conductance, spin Hall angle and spin diffusion length. Our findings establish the purely spintronic nature of the aforementioned effects and provide a quantitative description in particular of the spin Seebeck effect.Pure spin currents present a new paradigm in spintronics [1, 2] and spin caloritronics [3]. In particular, spin currents are the origin of spin pumping [4,5], the spin Seebeck effect [6,7] and the spin Hall magnetoresistance (SMR) [8][9][10]. Taken alone, all these effects have been extensively studied, both experimentally [6-9, 11-13] and theoretically [4,[14][15][16][17][18]. From a theoretical point of view, all these effects are governed by the generation of a current of angular momentum via a non-equilibrium process. The flow of this spin current across a ferromagnet/normal metal interface can then be detected. The relevant interface property that determines the spin current transport thereby is the spin mixing conductance. Nevertheless, there has been an ongoing debate regarding the physical origin of the measurement data acquired in spin Seebeck and SMR experiments due to possible contamination with anomalous Nernst effect [19][20][21] or anisotropic magnetoresistance [22,23] caused by static proximity polarization of the normal metal [23]. To settle this issue, a rigorous check of the consistency of the spin-current based physical models across all three effects is needed. If possible contamination effects are absent, according to the spin mixing conductance concept [24], there should exist a generalized Ohm's law between the interfacial spin current and the energy associated with the corresponding non-equilibrium process. This relation should invariably hold for the spin pumping, spin Seebeck and spin Hall magnetoresistance effects, as they are all based on the generation and detection of interfacial, nonequilibrium spin currents. We here put forward heuristic arguments that are strongly supported by experimental evidence for a scaling law that links all aforementioned spin(calori)tronic effects on a fundamental level and allows to trace back their origin to pure spin currents. (c) The spin Hall magnetoresistance is due to the torque exerted on M by an appropriately polarized Js which yields a change in the reflected spin current J r s . The interconversion between Js (J r s ) and the charge currents Jc (J r c ) are due to the (inverse) spin Hall effect in the normal metal.[schematically depicted in Fig. 1(a)], we place YIG / Pt bilayers in a microwave cavity operated at ν = 9.85 GHz to resonantly excite magnetization dynamics. The emission of a spin current density J s across the bilayer interface into the Pt provides...

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“…Under a perpendicular temperature gradient ∇ z T, the ANE of E ANE ∝ ∇ Z T × M gives rise to a transverse voltage, where M is magnetization of the ferromagnet. 10,21 Both longitudinal SSE and ANE have the same field dependence and thus inseparable. Therefore, the unequivocal establishment of the longitudinal SSE in Pt/YIG is contingent upon separating the ANE contribution, if any.…”

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confidence: 99%

Absence of anomalous Nernst effect in spin Seebeck effect of Pt/YIG

Miao

Huang

et al. 2016

AIP Advances

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The Pt/YIG structure has been widely used to study spin Seebeck effect (SSE), inverse spin Hall effect, and other pure spin current phenomena. However, the magnetic proximity effect in Pt when in contact with YIG, and the potential anomalous Nernst effect (ANE) may compromise the spin current phenomena in Pt/YIG. By inserting a Cu layer of various thicknesses between Pt and YIG, we have separated the signals from the SSE and that of the ANE. It is demonstrated that the thermal voltage in Pt/YIG mainly comes from spin current due to the longitudinal SSE with negligible contribution from the ANE.

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Ueber die electromotorischen Kräfte, welche durch den Magnetismus in von einem Wärmestrome durchflossenen Metallplatten geweckt werden

Cited by 85 publications

References 3 publications

Thickness dependence of unidirectional spin-Hall magnetoresistance in metallic bilayers

Thickness dependence of unidirectional spin-Hall magnetoresistance in metallic bilayers

Experimental Test of the Spin Mixing Interface Conductivity Concept

Absence of anomalous Nernst effect in spin Seebeck effect of Pt/YIG

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