Spin Seebeck effect detection by harmonic analysis (original) (raw)
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Supplementary Material: Spin Seebeck effect detection by harmonic analysis
The application of a static thermal gradient (∇ ∇ ∇T ) across the bilayer interface along the z−direction and an alternating magnetic field (H H H ext (t) = H 0 sin(ωt)), parallel to the sample plane along the ±x−direction (∇ ∇ ∇T ⊥ H H H ext ), generate an electromotive force (EMF) in the Pt layer along the y−direction. The equivalent circuit model for the Pt/YIG bilayer film utilized in this work is shown in (a). In this model, the Pt layer acts as an ac-voltage source composed of two ideal ac-voltage sources connected in series. The electrical resistance (R) of the Pt layer acts as a load resistor. V H is the voltage induced by the variation of the magnetic field flux through the circuit loop done by the Faraday's law of induction. V SSE is originated, via inverse spin Hall effect (ISHE), by the conversion of the spin current (produced by the SSE) and injected in the Pt layer from the YIG layer along the z−direction, into an electric field (E E E ISHE ).
Journal of Magnetics, 2022
In this study, spin Seebeck effect (SSE) signals caused by a thermal gradient induced by Joule and laser heating were examined. A Pt/Y 3 Fe 5 O 12 /Gd 3 Ga 5 O 12 sample was used as the reference for SSE measurement. Both the Joule heating-and laser heating-based SSE measurement systems captured SSE hysteresis loops consistent with the magnetic hysteresis loop of the sample. The laser heating-based system measured a higher SSE signal; however, heat flux could not be precisely evaluated. With the Joule heating-based system, the spin Seebeck resistivity (SSR) was 21.2 ± 1 nm/A, comparable with the values obtained in other studies and indicating the feasibility of our apparatus for investigating SSE.
Nature communications, 2015
The spin Seebeck effect, the generation of a spin current by a temperature gradient, has attracted great attention, but the interplay over a millimetre range along a thin ferromagnetic film as well as unintended side effects which hinder an unambiguous detection have evoked controversial discussions. Here, we investigate the inverse spin Hall voltage of a 10 nm thin Pt strip deposited on the magnetic insulators Y3Fe5O12 and NiFe2O4 with a temperature gradient in the film plane. We show characteristics typical of the spin Seebeck effect, although we do not observe the most striking features of the transverse spin Seebeck effect. Instead, we attribute the observed voltages to the longitudinal spin Seebeck effect generated by a contact tip induced parasitic out-of-plane temperature gradient, which depends on material, diameter and temperature of the tip.
Interplay of spin-orbit torque and thermoelectric effects in ferromagnet/normal-metal bilayers
Physical Review B, 2014
We present harmonic transverse voltage measurements of current-induced thermoelectric and spin-orbit torque (SOT) effects in ferromagnet/normal metal bilayers, in which thermal gradients produced by Joule heating and SOT coexist and give rise to ac transverse signals with comparable symmetry and magnitude. Based on the symmetry and field-dependence of the transverse resistance, we develop a consistent method to separate thermoelectric and SOT measurements. By arXiv:1412.0865v1 [cond-mat.mes-hall]
Observation of the spin-Seebeck effect in a ferromagnetic semiconductor
Nature Materials, 2010
The spin-Seebeck effect was recently discovered in a metallic ferromagnet and consists of a thermally generated spin distribution that is electrically measured utilizing the inverse spin Hall effect. Here this effect is reproduced experimentally in a ferromagnetic semiconductor, GaMnAs, which allows for flexible design of the magnetization directions, a larger spin polarization, and measurements across the magnetic phase transition. The spin-
Giant spin Seebeck effect in a non-magnetic material
Nature, 2012
The spin Seebeck effect is observed when a thermal gradient applied to a spin-polarized material leads to a spatially varying transverse spin current in an adjacent non-spin-polarized material, where it gets converted into a measurable voltage. It has been previously observed with a magnitude of microvolts per kelvin in magnetically ordered materials, ferromagnetic metals 1 , semiconductors 2 and insulators 3 . Here we describe a signal in a non-magnetic semiconductor (InSb) that has the hallmarks of being produced by the spin Seebeck effect, but is three orders of magnitude larger (millivolts per kelvin). We refer to the phenomenon that produces it as the giant spin Seebeck effect. Quantizing magnetic fields spin-polarize conduction electrons in semiconductors by means of Zeeman splitting, which spin-orbit coupling amplifies by a factor of 25 in InSb. We propose that the giant spin Seebeck effect is mediated by phonon-electron drag, which changes the electrons' momentum and directly modifies the spin-splitting energy through spin-orbit interactions. Owing to the simultaneously strong phonon-electron drag and spin-orbit coupling in InSb, the magnitude of the giant spin Seebeck voltage is comparable to the largest known classical thermopower values.
Physical Review B, 2013
The spin currents generated by thermal gradients through the spin Seebeck effect (SSE) are usually detected by the voltage generated in a normal metal by means of the inverse spin Hall effect. Here, we present a detailed account of an experimental investigation of the action of spin currents due to SSE on the relaxation rate of spin waves. Propagating spin-wave packets with a frequency in the range of 1-2 GHz are launched in film strips of single-crystal yttrium iron garnet, Y 3 Fe 5 O 12 (YIG) while a thermal gradient is applied across the thickness in the so-called longitudinal SSE configuration. No change in damping is observed in bare YIG films. However, if the YIG film is covered with an ultrathin platinum layer, we observe a striking change in the amplitude of the detected spin-wave pulses. Depending on the sign of the gradient, the spin-wave relaxation rate can be increased or decreased, leading in the latter case to an apparent amplification. The change in the relaxation rate is attributed to the action of a spin current generated in the YIG film by the SSE while the role of the Pt layer is to supply or absorb the flow of spins.