On the quality of molecular-beam epitaxy grown Fe/MgO and Co/MgO(001) interfaces

Journal Article · Sat Apr 15 00:00:00 EDT 2006 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.2165914· OSTI ID:20788113

Sicot, M; Andrieu, S; Tiusan, C; Montaigne, F; Bertran, F ^[1]

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1. Laboratoire de Physique des Materiaux, CNRS, University of H. Poincare, 54506 Vandoeuvre (France)

We investigated in detail the structural, chemical, and magnetic properties of Fe at the interface with MgO. The samples were grown by molecular-beam epitaxy and analyzed by using reflection high-energy electron diffraction, scanning tunneling microscopy, Auger electron spectroscopy, x-ray photoemission spectroscopy (XPS), x-ray-absorption spectroscopy (XAS), and x-ray magnetic circular dichroism (XMCD) measurements. We discuss the presence or absence of C and O contaminants at the surface of the metallic film. We actually show that when growing the first Fe layer on the initial MgO substrate, a carbon contamination at the surface of the annealed Fe layer is observed leading to a C(2x2) surface structure. We propose a method to eliminate this carbon contamination and to get interfaces free of carbon. On the other hand, we observed that the reactivity of the Fe surface to oxygen contamination is greatly influenced by the presence of carbon or absence on the surface. The influence of oxygen adsorption at the Fe surface on the MgO growth will also be discussed. Concerning the hybridization between Fe or Co with MgO, XPS, and XAS-XMCD analyses clearly demonstrate that the charge transfer is weak, and that the magnetization at the interface is larger than in bulk (3{mu}{sub B}/at for Fe). With such clean interfaces, reproducible magnetoresistance equal to 160% are obtained on Fe/MgO(3 nm)/Fe(001) 100x100 {mu}m{sup 2} tunnel junctions at room temperature in our laboratory. Finally, we show that pollution at the bottom Fe/MgO interface modify drastically spin-dependent tunneling properties.

• OSTI ID: 20788113
• Journal Information: Journal of Applied Physics, Vol. 99, Issue 8; Other Information: DOI: 10.1063/1.2165914; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ABSORPTION SPECTROSCOPY
AUGER ELECTRON SPECTROSCOPY
CARBON
CHARGE EXCHANGE
COBALT
ELECTRON DIFFRACTION
IRON
MAGNESIUM OXIDES
MAGNETIC CIRCULAR DICHROISM
MAGNETIC PROPERTIES
MAGNETORESISTANCE
MOLECULAR BEAM EPITAXY
OXYGEN
PHOTOEMISSION
SCANNING TUNNELING MICROSCOPY
SUPERCONDUCTING JUNCTIONS
TEMPERATURE RANGE 0273-0400 K
TUNNEL EFFECT
X-RAY PHOTOELECTRON SPECTROSCOPY
X-RAY SPECTROSCOPY