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Local Environmental Effects in Magnetic Alloys and Multilayers: Calculations of the Static Response Functions

Published online by Cambridge University Press:  21 February 2011

D. D. Johnson
Affiliation:
Theoretical Division, Sandia National Laboratories, Livermore, CA
J. B. Staunton
Affiliation:
Department of Physics, University of Warwick, Coventry, U.K
B. L. Györffy
Affiliation:
H.H. Wills Physics Laboratory, University of Bristol, Bristol, U.K.
F. J. Pinski
Affiliation:
Department of Physics, University of Cincinnati, Cincinnati, OH
G. M. Stocks
Affiliation:
Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, TN
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Abstract

We have developed an ab-initio method for calculating the static response functions in substitutional alloys. For magnetic alloys, in addition to the nuclear diffuse scattering, a contribution to the alloy diffuse scattering intensities results from the response of the local moments to changes in the ‘local’ chemical environment (i.e. ∂μi/∂cj). We present results of firstprinciples calculations of these ‘local’ response functions in magnetic alloys. These response functions, which may be directly compared to neutron-scattering and Mößbauer experiments, are derived via a mean-field statistical mechanical description of compositional fluctuations in alloys. The statistical averages are performed via the Korringa-Kohn-Rostoker coherent potential approximation, which incorporates the electronic structure of the high-temperature, chemically disordered state. As a first application of the theory, we have investigated the environmental dependence of the moments in NiFe alloys and FeV alloys and multilayers. We compare our results with experiments on bulk alloys and multilayers. Also, a comparison is made to a set of first-principle ‘supercell’ calculations. Although preliminary, the results demonstrate the utility of these response functions for investigating the effects of changes in the chemical environment on the alloy moments and for aiding experimental interpretation in other multilayer systems that are less experimentally amenable than FeV.

Type
Research Article
Copyright
Copyright © Materials Research Society 1990

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References

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