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

Journal Article · Thu Nov 07 00:00:00 EST 2019 · Nano Letters

DOI:https://doi.org/10.1021/acs.nanolett.9b03190· OSTI ID:1573371

Li, Xiang ^[1]; Sasaki, Taisuke ^[2]; Grezes, Cecile ^[3]; Wu, Di ^[3]; Wong, Kin L. ^[3]; Bi, Chong ^[4]; Ong, Phuong-Vu ^[5]; Ebrahimi, Farbod ^[6]; Yu, Guoqiang ^[3]; Kioussis, Nicholas ^[5]; Wang, Weigang ^[4]; Ohkubo, Tadakatsu ^[2]; Khalili Amiri, Pedram ^[7]; Wang, Kang L. ^[3]

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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

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.

• Research Organization: Univ. of California, Riverside, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: SC0012670
• OSTI ID: 1573371
• Journal Information: Nano Letters, Vol. 19, Issue 12; ISSN 1530-6984
• Publisher: American Chemical Society
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
voltage-controlled magnetic anisotropy
perpendicular magnetic anisotropy
tunneling magnetoresistance
crystal structure
element distribution
magnetic tunnel junction