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Nanosecond Structural Transformation of Magnetic thin Films: PtMnSb, Structure and Magnetic Properties

Published online by Cambridge University Press:  15 February 2011

Yukiko Kubota
Affiliation:
IBM Research Division, Almaden Research Center, 650 Harry Road, San Jose, CA 95120-6099 Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305
Ernesto E. Marinero
Affiliation:
IBM Research Division, Almaden Research Center, 650 Harry Road, San Jose, CA 95120-6099
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Abstract

We report on the phase transformation of amorphous PtMnSb thin films induced by laser annealing in the nanosecond time regime. Structural and magnetic transformations are investigated by TEM, XRD, AFM and in-situ MOKE and VSM. We have established that a minimum laser fluence is required to crystallize the amorphous films and thus, to induce magnetic activity. The transformation kinetics vs number of irradiation pulses reveals that the magnetically active C1b phase is formed via an intermediate phase, namely, tetragonal-PtMn. We have also established that the thin film crystallization induced by the nanosecond laser annealing proceeds via nucleation rather than grain growth. Measurement of the lattice parameter of the C1b-PtMnSb produced by the laser quenching (LQ) indicates an essentially unstrained structure with a =6.17 Å vs a =6.201 Å reported for the bulk. Nevertheless, we observe the generation of large surface undulations upon laser annealing and suggest that this is the mechanism for stress relaxation concomitant with the large volumetric changes involved in the phase transformation. In addition, we observe decrements in saturation moments and Curie temperatures which are attributed to the nanocrystalline nature of the LQ specimens.

Type
Research Article
Copyright
Copyright © Materials Research Society 1995

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References

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