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Title: Predictive Materials Design of Magnetic Random-Access Memory Based on Nanoscale Atomic Structure and Element Distribution

Abstract

Magnetic tunnel junctions (MTJs) capable of electrical read and write operations have emerged as a canonical building block for non-volatile memory and logic. However, the cause of the wide-spread device properties found experimentally in various MTJ stacks, including tunneling magnetoresistance (TMR), perpendicular magnetic anisotropy (PMA), and voltage-controlled magnetic anisotropy (VCMA), remains elusive. Here, using high-resolution transmission electron microscopy and energy-dispersive X-ray spectroscopy, we found that the MTJ crystallization quality, boron diffusion out of the CoFeB fixed layer, and minimal CoFe oxidation correlate with the TMR. As with the CoFeB free layer, seed layer diffusion into the free layer/MgO interface is negatively correlated with the interfacial PMA, while the metal-oxides concentrations in the free layer correlate with the VCMA. Combined with formation enthalpy and thermal diffusion analysis, we further established a predictive materials design framework to guide the complex design space explorations for high-performance MTJs. In this paper, we demonstrate experimentally high PMA and VCMA values of 1.74 mJ/m2 and 115 fJ/V-m with annealing stability above 400 °C.

Authors:
 [1];  [2];  [3];  [3];  [3];  [4];  [5];  [6];  [3];  [5];  [4];  [2];  [7];  [3]
  1. Univ. of California, Los Angeles, CA (United States). Dept. of Electrical and Computer Engineering; Inston, Inc., Los Angeles, CA (United States); Stanford Univ., CA (United States). Dept. of Electrical Engineering
  2. National Inst. for Materials Science (NIMS), Tsukuba (Japan)
  3. Univ. of California, Los Angeles, CA (United States). Dept. of Electrical and Computer Engineering
  4. Univ. of Arizona, Tucson, AZ (United States). Dept. of Physics
  5. California State Univ. Northridge, CA (United States).Dept. of Physics and Astronomy
  6. Inston, Inc., Los Angeles, CA (United States); Happy Electron Lab Inc., Redwood City, CA (United States)
  7. Univ. of California, Los Angeles, CA (United States). Dept. of Electrical and Computer Engineering; Northwestern Univ., Evanston, IL (United States). Dept. of Electrical Engineering and Computer Science
Publication Date:
Research Org.:
Univ. of California, Riverside, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1573371
Grant/Contract Number:  
SC0012670
Resource Type:
Accepted Manuscript
Journal Name:
Nano Letters
Additional Journal Information:
Journal Name: Nano Letters; Journal ID: ISSN 1530-6984
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
voltage-controlled magnetic anisotropy; perpendicular magnetic anisotropy; tunneling magnetoresistance; crystal structure; element distribution; magnetic tunnel junction

Citation Formats

Li, Xiang, Sasaki, Taisuke, Grezes, Cecile, Wu, Di, Wong, Kin L., Bi, Chong, Ong, Phuong-Vu, Ebrahimi, Farbod, Yu, Guoqiang, Kioussis, Nicholas, Wang, Weigang, Ohkubo, Tadakatsu, Khalili Amiri, Pedram, and Wang, Kang L. Predictive Materials Design of Magnetic Random-Access Memory Based on Nanoscale Atomic Structure and Element Distribution. United States: N. p., 2019. Web. doi:10.1021/acs.nanolett.9b03190.
Li, Xiang, Sasaki, Taisuke, Grezes, Cecile, Wu, Di, Wong, Kin L., Bi, Chong, Ong, Phuong-Vu, Ebrahimi, Farbod, Yu, Guoqiang, Kioussis, Nicholas, Wang, Weigang, Ohkubo, Tadakatsu, Khalili Amiri, Pedram, & Wang, Kang L. Predictive Materials Design of Magnetic Random-Access Memory Based on Nanoscale Atomic Structure and Element Distribution. United States. doi:10.1021/acs.nanolett.9b03190.
Li, Xiang, Sasaki, Taisuke, Grezes, Cecile, Wu, Di, Wong, Kin L., Bi, Chong, Ong, Phuong-Vu, Ebrahimi, Farbod, Yu, Guoqiang, Kioussis, Nicholas, Wang, Weigang, Ohkubo, Tadakatsu, Khalili Amiri, Pedram, and Wang, Kang L. Thu . "Predictive Materials Design of Magnetic Random-Access Memory Based on Nanoscale Atomic Structure and Element Distribution". United States. doi:10.1021/acs.nanolett.9b03190.
@article{osti_1573371,
title = {Predictive Materials Design of Magnetic Random-Access Memory Based on Nanoscale Atomic Structure and Element Distribution},
author = {Li, Xiang and Sasaki, Taisuke and Grezes, Cecile and Wu, Di and Wong, Kin L. and Bi, Chong and Ong, Phuong-Vu and Ebrahimi, Farbod and Yu, Guoqiang and Kioussis, Nicholas and Wang, Weigang and Ohkubo, Tadakatsu and Khalili Amiri, Pedram and Wang, Kang L.},
abstractNote = {Magnetic tunnel junctions (MTJs) capable of electrical read and write operations have emerged as a canonical building block for non-volatile memory and logic. However, the cause of the wide-spread device properties found experimentally in various MTJ stacks, including tunneling magnetoresistance (TMR), perpendicular magnetic anisotropy (PMA), and voltage-controlled magnetic anisotropy (VCMA), remains elusive. Here, using high-resolution transmission electron microscopy and energy-dispersive X-ray spectroscopy, we found that the MTJ crystallization quality, boron diffusion out of the CoFeB fixed layer, and minimal CoFe oxidation correlate with the TMR. As with the CoFeB free layer, seed layer diffusion into the free layer/MgO interface is negatively correlated with the interfacial PMA, while the metal-oxides concentrations in the free layer correlate with the VCMA. Combined with formation enthalpy and thermal diffusion analysis, we further established a predictive materials design framework to guide the complex design space explorations for high-performance MTJs. In this paper, we demonstrate experimentally high PMA and VCMA values of 1.74 mJ/m2 and 115 fJ/V-m with annealing stability above 400 °C.},
doi = {10.1021/acs.nanolett.9b03190},
journal = {Nano Letters},
number = ,
volume = ,
place = {United States},
year = {2019},
month = {11}
}

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This content will become publicly available on November 7, 2020
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