Fabrication of yttrium-iron-garnet/Pt multilayers for the longitudinal spin Seebeck effect

Tatsuhiro Nozue; Takashi Kikkawa; Tomoki Watamura; Tomohiko Niizeki; Rafael Ramos; Eiji Saitoh; Hirohiko Murakami

doi:10.1063/1.5046977

Fabrication of yttrium-iron-garnet/Pt multilayers for the longitudinal spin Seebeck effect

Tatsuhiro Nozue, Takashi Kikkawa, Tomoki Watamura, Tomohiko Niizeki, Rafael Ramos, Eiji Saitoh, Hirohiko Murakami

Advanced Institute for Materials Research (AIMR)

Research output: Contribution to journal › Article › peer-review

9 Citations (Scopus)

Abstract

For longitudinal spin Seebeck effect (LSSE) devices, a multilayer structure comprising ferromagnetic and nonmagnetic layers is expected to improve their thermoelectric power. In this study, we developed a fabrication method for alternately stacked yttrium-iron-garnet (YIG)/Pt multilayer films on a gadolinium gallium garnet (GGG) (110) substrate, GGG/[YIG(49 nm)/Pt(4 nm)] _n (n = 1-5) based on room-temperature sputtering and ex-situ post-annealing methods and we evaluated their structural and LSSE properties. The fabricated [YIG/Pt] _n samples show flat YIG/Pt interfaces and almost identical saturation magnetization M _s although they contain polycrystalline YIG layers on Pt layers as well as single-crystalline YIG layers on GGG. In the samples, we observed clear LSSE signals and found that the LSSE thermoelectric power factor (PF) increases monotonically with increasing n; the PF of the [YIG/Pt] ₅ sample is enhanced by a factor of ∼28 compared to that of [YIG/Pt] ₁ . This work may provide a guideline for developing future multilayer-based LSSE devices.

Original language	English
Article number	262402
Journal	Applied Physics Letters
Volume	113
Issue number	26
DOIs	https://doi.org/10.1063/1.5046977
Publication status	Published - 2018 Dec 24

ASJC Scopus subject areas

Physics and Astronomy (miscellaneous)

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10.1063/1.5046977

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@article{80db62415e46424997adb51525a431f9,

title = "Fabrication of yttrium-iron-garnet/Pt multilayers for the longitudinal spin Seebeck effect",

abstract = " For longitudinal spin Seebeck effect (LSSE) devices, a multilayer structure comprising ferromagnetic and nonmagnetic layers is expected to improve their thermoelectric power. In this study, we developed a fabrication method for alternately stacked yttrium-iron-garnet (YIG)/Pt multilayer films on a gadolinium gallium garnet (GGG) (110) substrate, GGG/[YIG(49 nm)/Pt(4 nm)] n (n = 1-5) based on room-temperature sputtering and ex-situ post-annealing methods and we evaluated their structural and LSSE properties. The fabricated [YIG/Pt] n samples show flat YIG/Pt interfaces and almost identical saturation magnetization M s although they contain polycrystalline YIG layers on Pt layers as well as single-crystalline YIG layers on GGG. In the samples, we observed clear LSSE signals and found that the LSSE thermoelectric power factor (PF) increases monotonically with increasing n; the PF of the [YIG/Pt] 5 sample is enhanced by a factor of ∼28 compared to that of [YIG/Pt] 1 . This work may provide a guideline for developing future multilayer-based LSSE devices. ",

author = "Tatsuhiro Nozue and Takashi Kikkawa and Tomoki Watamura and Tomohiko Niizeki and Rafael Ramos and Eiji Saitoh and Hirohiko Murakami",

note = "Funding Information: The authors thank S. Ito from the Institute for Materials Research, Tohoku University, for performing TEM and STEM on our samples and also thank T. Hioki, Y. Oikawa, K. Harii, Y. Ohnuma, and M. Matsuo for fruitful discussions. This work was supported by ERATO “Spin Quantum Rectification Project” (JPMJER1402) from JST, a Grant-in-Aid for Scientific Research on Innovative Area “Nano Spin Conversion Science” (JP26103005) and a Grant-in-Aid for Research Activity Start-up (JP18H05841) from JSPS KAKENHI, and ULVAC, Inc. Publisher Copyright: {\textcopyright} 2018 Author(s).",

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AU - Nozue, Tatsuhiro

AU - Kikkawa, Takashi

AU - Watamura, Tomoki

AU - Niizeki, Tomohiko

AU - Ramos, Rafael

AU - Saitoh, Eiji

AU - Murakami, Hirohiko

N1 - Funding Information: The authors thank S. Ito from the Institute for Materials Research, Tohoku University, for performing TEM and STEM on our samples and also thank T. Hioki, Y. Oikawa, K. Harii, Y. Ohnuma, and M. Matsuo for fruitful discussions. This work was supported by ERATO “Spin Quantum Rectification Project” (JPMJER1402) from JST, a Grant-in-Aid for Scientific Research on Innovative Area “Nano Spin Conversion Science” (JP26103005) and a Grant-in-Aid for Research Activity Start-up (JP18H05841) from JSPS KAKENHI, and ULVAC, Inc. Publisher Copyright: © 2018 Author(s).

PY - 2018/12/24

Y1 - 2018/12/24

N2 - For longitudinal spin Seebeck effect (LSSE) devices, a multilayer structure comprising ferromagnetic and nonmagnetic layers is expected to improve their thermoelectric power. In this study, we developed a fabrication method for alternately stacked yttrium-iron-garnet (YIG)/Pt multilayer films on a gadolinium gallium garnet (GGG) (110) substrate, GGG/[YIG(49 nm)/Pt(4 nm)] n (n = 1-5) based on room-temperature sputtering and ex-situ post-annealing methods and we evaluated their structural and LSSE properties. The fabricated [YIG/Pt] n samples show flat YIG/Pt interfaces and almost identical saturation magnetization M s although they contain polycrystalline YIG layers on Pt layers as well as single-crystalline YIG layers on GGG. In the samples, we observed clear LSSE signals and found that the LSSE thermoelectric power factor (PF) increases monotonically with increasing n; the PF of the [YIG/Pt] 5 sample is enhanced by a factor of ∼28 compared to that of [YIG/Pt] 1 . This work may provide a guideline for developing future multilayer-based LSSE devices.

AB - For longitudinal spin Seebeck effect (LSSE) devices, a multilayer structure comprising ferromagnetic and nonmagnetic layers is expected to improve their thermoelectric power. In this study, we developed a fabrication method for alternately stacked yttrium-iron-garnet (YIG)/Pt multilayer films on a gadolinium gallium garnet (GGG) (110) substrate, GGG/[YIG(49 nm)/Pt(4 nm)] n (n = 1-5) based on room-temperature sputtering and ex-situ post-annealing methods and we evaluated their structural and LSSE properties. The fabricated [YIG/Pt] n samples show flat YIG/Pt interfaces and almost identical saturation magnetization M s although they contain polycrystalline YIG layers on Pt layers as well as single-crystalline YIG layers on GGG. In the samples, we observed clear LSSE signals and found that the LSSE thermoelectric power factor (PF) increases monotonically with increasing n; the PF of the [YIG/Pt] 5 sample is enhanced by a factor of ∼28 compared to that of [YIG/Pt] 1 . This work may provide a guideline for developing future multilayer-based LSSE devices.

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Fabrication of yttrium-iron-garnet/Pt multilayers for the longitudinal spin Seebeck effect

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