Spin Seebeck effect and spin Hall magnetoresistance at high temperatures for a Pt/yttrium iron garnet hybrid structure

Wang, Shuanhu; Zou, Lvkuan; Zhang, Xu; Cai, Jianwang; Wang, Shufang; Shen, Baogen; Sun, J. R.

doi:10.1039/c5nr05484b

Cited by 28 publications

(28 citation statements)

References 40 publications

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“…As reported previously [8,16,20], materials with large negative spin Hall angle such as β- In addition to finding materials that show the largest possible V SSE voltages in response to applied temperature differences, it is equally important to understand the underlying mechanisms and how the experimental results correlate with theoretical predictions. For this we performed temperature dependent V SSE measurements over the temperature range 4-298 K. Early theoretical studies by Xiao et al [17,21] predicted that V SSE in longitudinal YIG/Pt device should monotonically decrease with decreasing base temperature. This prediction was based on the assumption that the population of magnons in YIG decreases on decreasing the temperature.…”

Section: Resultsmentioning

confidence: 99%

β-Tantalum, a better candidate for spin-to-charge conversion

Magginetti

Tian

Tiwari

2017

Solid State Communications

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Development of thermoelectric energy harvesting devices has hit a stumbling block due to the intrinsically linked electrical and thermal conductivities of materials. However, this field can still be improved by employing devices that take advantage of spin-based effects. A temperature gradient can be converted to a spin-polarized current in a ferrimagnetic insulator by the spin Seebeck effect (SSE), and that spin current can be converted to an electrical voltage in a heavy metal by the Inverse spin Hall effect (ISHE). Thus, the thermal energy capture and charge production steps can be separated into two distinct regions of the thermoelectric device, allowing separate tuning of electrical and thermal conductivities. The second step of this process, spin current to electrical voltage conversion, is controlled by the strength and sign of ISHE in the metal, and platinum has become the standard for this purpose. However, here we report a better candidate, β-Tantalum, which shows a spin Seebeck voltage approximately 4 times higher than that of Pt at room temperature. The temperature dependence of spin Seebeck in YIG/β-Ta also closely follows that of YIG/Pt, consistent with magnon spin current theory. The sign of the spin Seebeck voltage in Ta found to be opposite to that of Pt, making the two materials highly complementary for fabricating spintronics-based thermoelectric modules for practical applications.

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Section: Resultsmentioning

confidence: 99%

β-Tantalum, a better candidate for spin-to-charge conversion

Magginetti

Tian

Tiwari

2017

Solid State Communications

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“…On the other hand, Rezende et al proposed "bulk magnon spin current model" assuming that spin current J S produced in FMI by the temperature gradient ∇T is injected into the PM layer at a PM/FMI junction. [6][7][8][9] In that model, the factor tFMI was introduced to reflect the effect of FMI thickness, and the J S vector was defined as follows:…”

Section: Acknowledgmentmentioning

confidence: 99%

“…Theoretical studies on an appearance of J S due to ∇T in FMI and its spin injection (pumping) into the PM layer from the FMI were initially based on so called “thermal interfacial spin pumping model” assuming that the origin is thermal non‐equilibrium between the localized spin (magnon) system in the FMI and the conduction electron system in the PM layer at the PM/FMI interface, and this approach has taken hold . On the other hand, “bulk magnon spin current model” was also proposed; this model assumes that the spin pumping at the PM/FMI interface is not caused by a temperature difference between the magnon system and conduction electron system, but J S produced in the FMI by ∇T is injected into the PM layer at the PM/FMI interface . In these important studies related to the basic principles of STE power generation, theoretical expressions for J S and V STE (or V ISHE ) were derived (shown in Appendix).…”

Section: Introductionmentioning

confidence: 99%

“…4,5 On the other hand, "bulk magnon spin current model" was also proposed; this model assumes that the spin pumping at the PM/FMI interface is not caused by a temperature difference between the magnon system and conduction electron system, but J S produced in the FMI by ∇T is injected into the PM layer at the PM/FMI interface. [6][7][8][9] In these important studies related to the basic principles of STE power generation, theoretical expressions for J S and V STE (or V ISHE ) were derived (shown in Appendix). A problem with STE conversion devices is how to increase the value of generated voltage V STE .…”

Section: Introductionmentioning

confidence: 99%

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Spin‐thermoelectric voltage in longitudinal SSE elements incorporating LPE YIG films and polycrystalline YIG slabs with an ultrathin Pt layer

Imamura

Asada

Tashima

et al. 2019

Electrical Engineering Japan

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A spin‐thermoelectric (STE) voltage is generated when a temperature gradient ∇T is applied to an element having a thin Pt layer coated on a magnetic substance. In this study, yttrium iron garnet (YIG) ferrimagnetic films prepared by liquid phase epitaxy (LPE) were tested as magnetic insulators. In addition, polycrystalline YIG slabs were tested to compare the STE voltages of film and slab samples. In a Pt coating and YIG film bilayer structure made by an ultrathin Pt layer of 1‐4 nm thickness and an LPE film of approximately 10 µm thickness, a large STE voltage of 600 µV was observed at a probe distance of 5 mm with a temperature difference ∆T of 30 K. On the other hand, the STE voltage of a Pt layer and YIG slab bilayer structure was 340 µV, which is roughly half of that of the Pt/YIG‐film element. The cause of the large voltage observed experimentally for the longitudinal spin Seebeck effect element incorporating an LPE YIG film was discussed mainly from the viewpoint of the Pt layer resistivity and the effects of YIG specimen surface conditions on crystallinity and the magnetization process.

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“…Compared to other spintronic devices, SMR studies are the simplest method to obtain spin current parameters (such as the spin Hall angle or spin diffusion length) and to characterize materials 23 – 26 . In the early stages of the SMR research, ferromagnetic insulators (FMIs) such as YIG and CoFe 2 O 4 (CFO) had been chosen as the magnetic layer 27 – 30 because this arrangement can ensure that all currents flow only in the HM layer. Furthermore, these studies also confirm the origin of SMR and provide plentiful results in different materials.…”

Section: Introductionmentioning

confidence: 99%

Interface-induced spin Hall magnetoresistance enhancement in Pt-based tri-layer structure

Huang

Chong

et al. 2018

Sci Rep

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In this study, we integrated bilayer structure of covered Pt on nickel zinc ferrite (NZFO) and CoFe/Pt/NZFO tri-layer structure by pulsed laser deposition system for a spin Hall magnetoresistance (SMR) study. In the bilayer structure, the angular-dependent magnetoresistance (MR) results indicate that Pt/NZFO has a well-defined SMR behavior. Moreover, the spin Hall angle and the spin diffusion length, which were 0.0648 and 1.31 nm, respectively, can be fitted by changing the Pt thickness in the longitudinal SMR function. Particularly, the MR ratio of the bilayer structure (Pt/NZFO) has the highest changing ratio (about 0.135%), compared to the prototype structure Pt/Y3Fe5O12 (YIG) because the NZFO has higher magnetization. Meanwhile, the tri-layer samples (CoFe/Pt/NZFO) indicate that the MR behavior is related with CoFe thickness as revealed in angular-dependent MR measurement. Additionally, comparison between the tri-layer structure with Pt/NZFO and CoFe/Pt bilayer systems suggests that the SMR ratio can be enhanced by more than 70%, indicating that additional spin current should be injected into Pt layer.

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Spin Seebeck effect and spin Hall magnetoresistance at high temperatures for a Pt/yttrium iron garnet hybrid structure

Cited by 28 publications

References 40 publications

β-Tantalum, a better candidate for spin-to-charge conversion

β-Tantalum, a better candidate for spin-to-charge conversion

Spin‐thermoelectric voltage in longitudinal SSE elements incorporating LPE YIG films and polycrystalline YIG slabs with an ultrathin Pt layer

Interface-induced spin Hall magnetoresistance enhancement in Pt-based tri-layer structure

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