X-ray absorption spectroscopy studies on magnetic tunnel junctions with AlO and AlN tunnel barriers

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

DOI:https://doi.org/10.1063/1.2176055· OSTI ID:20788121

Mun, B S; Moon, J C; Hong, S W; Kang, K S; Kim, K; Kim, T W; Ju, H L ^[1]

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1. Advanced Light Source, Lawrence Berkeley Laboratory, Berkeley, California 94720 (United States)

X-ray photoelectron spectroscopy (XPS) and x-ray absorption spectroscopy (XAS) measurements of the optimized magnetic tunnel junctions (MTJs) with AlO and AlN barriers have been performed to study the chemical structures of the barrier and the underlying layer. These MTJs with AlO and AlN barriers exhibited increased tunneling magnetoresistance (TMR) after annealing at 200 deg. C from 27% to 45% and from 25% to 33%, respectively. Surprisingly, the XPS and XAS measurements confirmed that both the as-grown and the annealed MTJs had metallic Co and Fe at the interface between the barrier and the underlying CoFe layer. After annealing, under-stoichiometric AlO{sub x} and AlN{sub x} phases in MTJs with AlO and AlN barriers partially transformed into stoichiometric Al{sub 2}O{sub 3} and AlN phases, respectively. Thus the increase in TMR after annealing for MTJs with clean interface between the barrier and the underlying layer is believed due to the anion redistribution inside the barrier layer, not from back diffusion from pinned magnetic layer to barrier layer.

• OSTI ID: 20788121
• Journal Information: Journal of Applied Physics, Vol. 99, Issue 8; Conference: 50. annual conference on magnetism and magnetic materials, San Jose, CA (United States), 30 Oct - 3 Nov 2005; Other Information: DOI: 10.1063/1.2176055; (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
ALUMINIUM NITRIDES
ALUMINIUM OXIDES
ANIONS
ANNEALING
COBALT ALLOYS
INTERFACES
IRON ALLOYS
LAYERS
MAGNETORESISTANCE
STOICHIOMETRY
SUPERCONDUCTING JUNCTIONS
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0400-1000 K
TUNNEL EFFECT
X-RAY PHOTOELECTRON SPECTROSCOPY
X-RAY SPECTRA
X-RAY SPECTROSCOPY