Magnetic Anisotropy and Thermal Stability of Ta-pinned Spin Valves

Published

January 1, 2001

Author(s)

R A. Fry, Robert D. McMichael, John E. Bonevich, P J. Chen, William F. Egelhoff Jr., Chang H. Lee

Abstract

It has recently been found that large uniaxial anisotropy fields in excess of 120 kA/m (1500 Oe) can be created in thin (3 nm to 5 nm) films of Co by obliquely sputtered Ta underlayers. This anisotropy can be used to pin the bottom film of a spin valve while having only a modest effect on the top free film, separated by a 2.5 nm Cu spacer layer. We describe measurements of magnetic anisotropy and thermalstability in these Ta-pinned spin valves. Using room temperature giant magnetoresistance (GMR) as a measure, we find that the structure is stable under cumulative 20 min anneals at 25 C intervals up to 300 C; GMR decreases to zero upon further anneals up to 450 C. Measurements taken at elevated temperatures reveal that GMR decreases linearly with temperature, extrapolating to zero atapproximately 425 C, while the anisotropy field is much less temperature dependent, remaining nearly constant up to 150 C and gradually decreasing to 50 % of its room temperature value at 325 C. The thermal stability of the large uniaxial anisotropy is comparable to that of the exchange bias in NiMn pinned films.

Citation

Magnetic Anisotropy and Thermal Stability of Ta-pinned Spin Valves

Volume

89

Issue

No. 11

Pub Type

Others

Keywords

giant magnetoresistance, GMR, magnetic anisotropy, spin valves, Ta-pinned spin valves

Citation

Fry, R. , McMichael, R. , Bonevich, J. , Chen, P. , Egelhoff, W. and Lee, C. (2001), Magnetic Anisotropy and Thermal Stability of Ta-pinned Spin Valves, Magnetic Anisotropy and Thermal Stability of Ta-pinned Spin Valves (Accessed April 20, 2025)