Spin transfer torque switching of hybrid memory layers with low Curie temperature CoPd/Pd multilayers

Wangzhen Zhao; Takumi Kimura; Takeshi Kato; Daiki Oshima; Yoshiaki Sonobe; Shigeki Takahashi; Satoshi Iwata

doi:10.1016/j.jmmm.2019.165749

Spin transfer torque switching of hybrid memory layers with low Curie temperature CoPd/Pd multilayers

Wangzhen Zhao, Takumi Kimura, Takeshi Kato^*, Daiki Oshima, Yoshiaki Sonobe, Shigeki Takahashi, Satoshi Iwata

^*Corresponding author for this work

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

Abstract

Thermally assisted spin transfer torque (STT) switching of hybrid memory stacks with a low Curie temperature (T_C) CoPd/Pd multilayers (MLs) and high T_C Co/Pd MLs were investigated. Current-perpendicular-to-the-plane giant-magneto-resistance (CPP-GMR) structures with a stack of [Co/Pt]₆/Cu/[Co/Pd]_M/[CoPd/Pd]_N (M + N = 3) were fabricated. The intrinsic critical current density (J_c0) and thermal stability factor Δ of the hybrid memory layer were evaluated from the STT-switching of the CPP-GMR. J_c0 and Δ were found to be almost independent of the pillar diameter, and the effective reversal size contributing to Δ was found to be much smaller than the physical pillar diameter. At room temperature, slight decreases of J_c0 and Δ were confirmed with increasing the thickness ratio of the low T_C MLs (N) in the hybrid memory layer. At high temperature of ~150 °C, J_c0 and Δ were found to significantly reduce, suggesting the thermally assisted STT switching by using the low T_C/high T_C hybrid memory layer.

Original language	English
Article number	165749
Journal	Journal of Magnetism and Magnetic Materials
Volume	493
DOIs	https://doi.org/10.1016/j.jmmm.2019.165749
Publication status	Published - 2020 Jan 1
Externally published	Yes

Keywords

Co based multilayer
Curie temperature
Exchange coupling
MRAM

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
Condensed Matter Physics

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10.1016/j.jmmm.2019.165749

Cite this

@article{e3f25e91b71e42c098a46b7955e49a3f,

title = "Spin transfer torque switching of hybrid memory layers with low Curie temperature CoPd/Pd multilayers",

abstract = "Thermally assisted spin transfer torque (STT) switching of hybrid memory stacks with a low Curie temperature (TC) CoPd/Pd multilayers (MLs) and high TC Co/Pd MLs were investigated. Current-perpendicular-to-the-plane giant-magneto-resistance (CPP-GMR) structures with a stack of [Co/Pt]6/Cu/[Co/Pd]M/[CoPd/Pd]N (M + N = 3) were fabricated. The intrinsic critical current density (Jc0) and thermal stability factor Δ of the hybrid memory layer were evaluated from the STT-switching of the CPP-GMR. Jc0 and Δ were found to be almost independent of the pillar diameter, and the effective reversal size contributing to Δ was found to be much smaller than the physical pillar diameter. At room temperature, slight decreases of Jc0 and Δ were confirmed with increasing the thickness ratio of the low TC MLs (N) in the hybrid memory layer. At high temperature of ~150 °C, Jc0 and Δ were found to significantly reduce, suggesting the thermally assisted STT switching by using the low TC/high TC hybrid memory layer.",

keywords = "Co based multilayer, Curie temperature, Exchange coupling, MRAM",

author = "Wangzhen Zhao and Takumi Kimura and Takeshi Kato and Daiki Oshima and Yoshiaki Sonobe and Shigeki Takahashi and Satoshi Iwata",

note = "Funding Information: The authors thank Mr. M. Kumazawa of Nagoya University for his assistance with the experiments. The authors are grateful for financial supports by JSPS KAKENHI Grant Numbers 16H04328 , 16K18091 , 17H03249 , 17K18878 . This work was also supported in part by the Project of Creation of Life Innovation Materials for Interdisciplinary and International Researcher Development of the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan. A part of this work was conducted at the Nagoya University Nanofabrication Platform, supported by “Nanotechnology Platform Program” of the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan. A part of this work was performed under the Research Program of “Dynamic Alliance for Open Innovation Bridging Human, Environment and Materials” in the “ Network Joint Research Center for Materials and Devices ”. Publisher Copyright: {\textcopyright} 2019 Elsevier B.V.",

year = "2020",

month = jan,

day = "1",

doi = "10.1016/j.jmmm.2019.165749",

language = "English",

volume = "493",

journal = "Journal of Magnetism and Magnetic Materials",

issn = "0304-8853",

publisher = "Elsevier",

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TY - JOUR

T1 - Spin transfer torque switching of hybrid memory layers with low Curie temperature CoPd/Pd multilayers

AU - Zhao, Wangzhen

AU - Kimura, Takumi

AU - Kato, Takeshi

AU - Oshima, Daiki

AU - Sonobe, Yoshiaki

AU - Takahashi, Shigeki

AU - Iwata, Satoshi

N1 - Funding Information: The authors thank Mr. M. Kumazawa of Nagoya University for his assistance with the experiments. The authors are grateful for financial supports by JSPS KAKENHI Grant Numbers 16H04328 , 16K18091 , 17H03249 , 17K18878 . This work was also supported in part by the Project of Creation of Life Innovation Materials for Interdisciplinary and International Researcher Development of the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan. A part of this work was conducted at the Nagoya University Nanofabrication Platform, supported by “Nanotechnology Platform Program” of the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan. A part of this work was performed under the Research Program of “Dynamic Alliance for Open Innovation Bridging Human, Environment and Materials” in the “ Network Joint Research Center for Materials and Devices ”. Publisher Copyright: © 2019 Elsevier B.V.

PY - 2020/1/1

Y1 - 2020/1/1

N2 - Thermally assisted spin transfer torque (STT) switching of hybrid memory stacks with a low Curie temperature (TC) CoPd/Pd multilayers (MLs) and high TC Co/Pd MLs were investigated. Current-perpendicular-to-the-plane giant-magneto-resistance (CPP-GMR) structures with a stack of [Co/Pt]6/Cu/[Co/Pd]M/[CoPd/Pd]N (M + N = 3) were fabricated. The intrinsic critical current density (Jc0) and thermal stability factor Δ of the hybrid memory layer were evaluated from the STT-switching of the CPP-GMR. Jc0 and Δ were found to be almost independent of the pillar diameter, and the effective reversal size contributing to Δ was found to be much smaller than the physical pillar diameter. At room temperature, slight decreases of Jc0 and Δ were confirmed with increasing the thickness ratio of the low TC MLs (N) in the hybrid memory layer. At high temperature of ~150 °C, Jc0 and Δ were found to significantly reduce, suggesting the thermally assisted STT switching by using the low TC/high TC hybrid memory layer.

AB - Thermally assisted spin transfer torque (STT) switching of hybrid memory stacks with a low Curie temperature (TC) CoPd/Pd multilayers (MLs) and high TC Co/Pd MLs were investigated. Current-perpendicular-to-the-plane giant-magneto-resistance (CPP-GMR) structures with a stack of [Co/Pt]6/Cu/[Co/Pd]M/[CoPd/Pd]N (M + N = 3) were fabricated. The intrinsic critical current density (Jc0) and thermal stability factor Δ of the hybrid memory layer were evaluated from the STT-switching of the CPP-GMR. Jc0 and Δ were found to be almost independent of the pillar diameter, and the effective reversal size contributing to Δ was found to be much smaller than the physical pillar diameter. At room temperature, slight decreases of Jc0 and Δ were confirmed with increasing the thickness ratio of the low TC MLs (N) in the hybrid memory layer. At high temperature of ~150 °C, Jc0 and Δ were found to significantly reduce, suggesting the thermally assisted STT switching by using the low TC/high TC hybrid memory layer.

KW - Co based multilayer

KW - Curie temperature

KW - Exchange coupling

KW - MRAM

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U2 - 10.1016/j.jmmm.2019.165749

DO - 10.1016/j.jmmm.2019.165749

M3 - Article

AN - SCOPUS:85071648170

VL - 493

JO - Journal of Magnetism and Magnetic Materials

JF - Journal of Magnetism and Magnetic Materials

SN - 0304-8853

M1 - 165749

ER -

Spin transfer torque switching of hybrid memory layers with low Curie temperature CoPd/Pd multilayers

Abstract

Keywords

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