Gigantic enhancement of spin Seebeck effect by phonon drag

Adachi, Hiroto; Uchida, K.; Saitoh, Eiji; Ohe, Jun–ichiro; Takahashi, Saburo; Maekawa, Sadamichi

doi:10.1063/1.3529944

Cited by 175 publications

(200 citation statements)

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“…In this paper, we show explicitly how temperature reduces the magnetic exchange amongst the nearest neighbors and increases the coupling between remote ones. The effective MPC that we find in Permalloy is consistent with the "phonon drag" theory of the spin Seebeck effect (SSE) [25][26][27]. Very recently [28], the temperature dependence of the SW stiffness was determined experimentally for thin films using ferromagnetic resonance (FMR) measurements.…”

Section: Introductionsupporting

confidence: 58%

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Competition of lattice and spin excitations in the temperature dependence of spin-wave properties

et al. 2018

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(2018). Competition of lattice and spin excitations in the temperature dependence of spin-wave properties. Physical Review B (PRB), 97 (21). The interplay of magnons and phonons can induce strong temperature variations in the magnetic exchange interactions, leading to changes in the magnetothermal response. This is a central mechanism in many magnetic phenomena, and in the new field of Spin Caloritronics, which focuses on the combination of heat and spin currents. Boson model systems have previously been developed to describe the magnon-phonon coupling but, until recently, studies rely on empirical parameters. In this paper, we propose a first-principles approach to describe the dependence of the magnetic exchange integrals on phonon renormalization, leading to changes in the magnon dispersion as a function of temperature. The temperature enters into the spin dynamics (by introducing fluctuations) as well as in the magnetic exchange itself. Depending on the strength of the coupling, these two temperatures may or may not be equilibrated, yielding different regimes. We test our approach in typical and well-known ferromagnetic materials: Ni, Fe, and Permalloy. We compare our results to recent experiments on the spin-wave stiffness, and discuss departures from Bloch's law and parabolic dispersion. Copyright and re-use policy

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Section: Introductionsupporting

confidence: 58%

“…A commonly proposed mechanism for the SSE is the propagation of out-of-equilibrium long-wavelength phonons in a crystalline substrate below the sample [27]. This enables a phonon-drag-like pumping of acoustic magnons in the magnetic material, and a resulting spin current which has a nonlocal origin.…”

Section: Discussionmentioning

confidence: 99%

Competition of lattice and spin excitations in the temperature dependence of spin-wave properties

et al. 2018

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“…Furthermore, the phononmagnon drag has been found to be very important [70][71][72]. In magnetic insulators conventional thermoelectrics cannot be applied.…”

Section: Spin Seebeck Effectmentioning

confidence: 99%

Spin caloritronics

2012

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“…It was predicted that phonons can play an important role in the spin Seebeck effect, leading to its huge enhancement. 36 Recent measurements of the spin Seebeck effect in multiple (Ga,Mn)As samples also suggest that the spin Seebeck effect can be driven by phonons. 37 In order to explain the main trends of the observed temperature and spatial dependence of the spin Seebeck effect in (Ga,Mn)As, a phenomenological model involving phonon-magnon coupling was introduced.…”

Section: Introductionmentioning

confidence: 99%

Theory of thermal spin-charge coupling in electronic systems

et al. 2012

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The interplay between spin transport and thermoelectricity offers several novel ways of generating, manipulating, and detecting nonequilibrium spin in a wide range of materials. Here, we formulate a phenomenological model in the spirit of the standard model of electrical spin injection to describe the electronic mechanism coupling charge, spin, and heat transport and employ the model to analyze several different geometries containing ferromagnetic (F) and nonmagnetic (N) regions: F, F/N, and F/N/F junctions, which are subject to thermal gradients. We present analytical formulas for the spin-accumulation and spin-current profiles in those junctions that are valid for both tunnel and transparent (as well as intermediate) contacts. For F/N junctions, we calculate the thermal spin-injection efficiency and the spin-accumulation-induced nonequilibrium thermopower. We find conditions for countering thermal spin effects in the N region with electrical spin injection. This compensating effect should be particularly useful for distinguishing electronic from other mechanisms of spin injection by thermal gradients. For F/N/F junctions, we analyze the differences in the nonequilibrium thermopower (and chemical potentials) for parallel and antiparallel orientations of the F magnetizations, as evidence and a quantitative measure of the spin accumulation in N. Furthermore, we study the Peltier and spin Peltier effects in F/N and F/N/F junctions and present analytical formulas for the heat evolution at the interfaces of isothermal junctions.

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Gigantic enhancement of spin Seebeck effect by phonon drag

Cited by 175 publications

References 19 publications

Competition of lattice and spin excitations in the temperature dependence of spin-wave properties

Competition of lattice and spin excitations in the temperature dependence of spin-wave properties

Spin caloritronics

Theory of thermal spin-charge coupling in electronic systems

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