Large tunnel magnetoresistance at room temperature with a Co{sub 2}FeAl full-Heusler alloy electrode

Journal Article · Mon Jun 06 00:00:00 EDT 2005 · Applied Physics Letters

DOI:https://doi.org/10.1063/1.1944893· OSTI ID:20702445

Okamura, S; Miyazaki, A; Sugimoto, S; Tezuka, N; Inomata, K ^[1]

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1. Department of Materials Science, Graduate School of Engineering, Tohoku University, Aoba-yama 6-6-02, Sendai 980-8579 (Japan)

Magnetic tunnel junctions (MTJs) with a Co{sub 2}FeAl Heusler alloy electrode are fabricated by the deposition of the film using an ultrahigh vacuum sputtering system followed by photolithography and Ar ion etching. A tunnel magnetoresistance (TMR) of 47% at room temperature (RT) are obtained in a stack of Co{sub 2}FeAl/Al-O{sub x}/Co{sub 75}Fe{sub 25} magnetic tunnel junction (MTJ) fabricated on a thermally oxidized Si substrate despite the A2 type atomic site disorder for Co{sub 2}FeAl. There is no increase of TMR in MTJs with the B2 type Co{sub 2}FeAl, which is prepared by the deposition on a heated substrate. X-ray photoelectron spectroscopy (XPS) depth profiles in Co{sub 2}FeAl single layer films reveal that Al atoms in Co{sub 2}FeAl are oxidized preferentially at the surfaces. On the other hand, at the interfaces in Co{sub 2}FeAl/Al-O{sub x}/Co{sub 75}Fe{sub 25} MTJs, the ferromagnetic layers are hardly oxidized during plasma oxidation for a formation of Al oxide barriers.

• OSTI ID: 20702445
• Journal Information: Applied Physics Letters, Vol. 86, Issue 23; Other Information: DOI: 10.1063/1.1944893; (c) 2005 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0003-6951
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM OXIDES
ARGON IONS
COBALT ALLOYS
DEPOSITION
ELECTRODES
ETCHING
FERROMAGNETIC MATERIALS
HEUSLER ALLOYS
INTERFACES
IRON ALLOYS
LAYERS
MAGNETORESISTANCE
OXIDATION
SPUTTERING
SUBSTRATES
SUPERCONDUCTING JUNCTIONS
TEMPERATURE RANGE 0273-0400 K
THIN FILMS
TUNNEL EFFECT
X-RAY PHOTOELECTRON SPECTROSCOPY