@article{794b98436617435cbad9afebecb789c5,
title = "Atomic-Scale Structure and Local Chemistry of CoFeB-MgO Magnetic Tunnel Junctions",
abstract = "Magnetic tunnel junctions (MTJs) constitute a promising building block for future nonvolatile memories and logic circuits. Despite their pivotal role, spatially resolving and chemically identifying each individual stacking layer remains challenging due to spatially localized features that complicate characterizations limiting understanding of the physics of MTJs. Here, we combine advanced electron microscopy, spectroscopy, and first-principles calculations to obtain a direct structural and chemical imaging of the atomically confined layers in a CoFeB-MgO MTJ, and clarify atom diffusion and interface structures in the MTJ following annealing. The combined techniques demonstrate that B diffuses out of CoFeB electrodes into Ta interstitial sites rather than MgO after annealing, and CoFe bonds atomically to MgO grains with an epitaxial orientation relationship by forming Fe(Co)-O bonds, yet without incorporation of CoFe in MgO. These findings afford a comprehensive perspective on structure and chemistry of MTJs, helping to develop high-performance spintronic devices by atomistic design.",
keywords = "atomic structure, CoFeB-MgO, local chemistry, magnetic tunnel junction, scanning transmission electron microscopy",
author = "Zhongchang Wang and Mitsuhiro Saito and McKenna, {Keith P.} and Shunsuke Fukami and Hideo Sato and Shoji Ikeda and Hideo Ohno and Yuichi Ikuhara",
note = "Funding Information: This work was supported in part by the JSPS Grant-in-Aid for Scientific Research on Innovative Areas {"}Nano Informatics{"} (Grant 26106503) and A (15H02290), the {"}Nanotechnology Platform{"} (project no. 12024046) at the University of Tokyo from the Ministry of Education, Culture, Sports, Science, and Technology (MEXT) of Japan, and R & D Project for ICT Key Technology to Realize Future Society of MEXT, ImPACT Program of CSTI, and JSPS Core to Core Program. M.S. thanks support from Scientific Research (C) (Grant 26420662). K.P.M. thanks support from EPSRC (Grant EP/K003151). This work made use of the facilities of Archer, the U.K.''s national high-performance computing service, via our membership in U.K. HPC Materials Chemistry Consortium, which is funded by the EPSRC (EP/L000202). A part of the calculations were conducted at Institute for Solid State Physics, University of Tokyo. Data relating to the density functional theory calculations performed during this research are available by request from the University of York Research database http://dx.doi.org/10.15124/b4750d52-dfc5-4188-8c96-79d7359446ff. Publisher Copyright: {\textcopyright} 2016 American Chemical Society.",
year = "2016",
month = mar,
day = "9",
doi = "10.1021/acs.nanolett.5b03627",
language = "English",
volume = "16",
pages = "1530--1536",
journal = "Nano Letters",
issn = "1530-6984",
publisher = "American Chemical Society",
number = "3",
}