Interface characterization of epitaxial Fe/MgO/Fe magnetic tunnel junctions

Journal Article · Sun Jan 01 04:00:00 EST 2012 · Journal of Nanoscience and Nanotechnology

DOI:https://doi.org/10.1166/jnn.2012.4257· OSTI ID:1073642

Wang, Shouguo ^[1]; Ward, R. C. C. ^[2]; Zhang, Xiaoguang ^[3]; Kohn, A. ^[2]; Ma, Q. L. ^[1]; Zhang, J. ^[1]; Liu, H. F. ^[1]; Han, Prof. X. F. ^[1]

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1. Institute of Physics, Chinese Academy of Science
2. University of Oxford
3. ORNL

Following predictions by first-principles theory of huge tunnel magnetoresistance (TMR) effect in epitaxial Fe/MgO/Fe magnetic tunnel junctions (MTJs), measured magnetoresistance (MR) ratio about 200% at room temperature (RT) have been reported in MgO-based epitaxial MTJs. Recently, MR ratio of about 600% has been reported at RT in MgO-based amorphous MTJs with core structure of CoFeB/MgO/CoFeB grown by magnetron sputtering with amorphous CoFeB layers. The sputtered CoFeB/MgO/CoFeB MTJs shows a great potential application in spintronic devices. Although epitaxial structure will probably not be used in devices, it remains an excellent model system to compare theoretical calculations with experimental results and to enhance our understanding of the spin dependent tunneling. Both theoretical calculations and experimental results clearly indicate that the interfacial structure plays a crucial role on coherent tunneling across single crystalMgO barrier, especially in epitaxial MgO-based MTJs grown by molecular beam epitaxy (MBE). Surface X-ray diffraction, Auger electron spectroscopy, X-ray absorption spectra, and X-ray magnetic circular dichroism have been used for interface characterization. However, no consistent viewpoint has been reached, and this is still an open issue. In this article, recent studies on the interface characterization in MgO-based epitaxial MTJs will be introduced, with a focus on research by X-ray photoelectron spectroscopy, high resolution transmission electron microscopy, and spin dependent tunneling spectroscopy.

• Research Organization: Oak Ridge National Laboratory (ORNL); Center for Nanophase Materials Sciences
• Sponsoring Organization: SC USDOE - Office of Science (SC)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1073642
• Journal Information: Journal of Nanoscience and Nanotechnology, Journal Name: Journal of Nanoscience and Nanotechnology Journal Issue: 2 Vol. 12; ISSN 1533-4880
• Country of Publication: United States
• Language: English