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Influence of normal and shear strain on magnetic anisotropy energy of hcp cobalt: An ab initio study

Published online by Cambridge University Press:  17 June 2013

Juan Wang*
Affiliation:
Institute of Industrial Science, The University of Tokyo, Tokyo 153-8505, Japan; andDepartment of Mechanical Engineering, The University of Tokyo, Tokyo 113-8656, Japan
Jan-Michael Albina
Affiliation:
Institute of Industrial Science, The University of Tokyo, Tokyo 153-8505, Japan
Tomio Iwasaki
Affiliation:
Advanced Simulation Department, Hitachi Research Laboratory, Hitachi, Ltd., Hitachinaka, Ibaraki 312-0034, Japan
Hiroshi Moriya
Affiliation:
Advanced Simulation Department, Hitachi Research Laboratory, Hitachi, Ltd., Hitachinaka, Ibaraki 312-0034, Japan
Yoshitaka Umeno
Affiliation:
Institute of Industrial Science, The University of Tokyo, Tokyo 153-8505, Japan
*
a)Address all correspondence to this author. e-mail: ouken@ulab.iis.u-tokyo.ac.jp
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Abstract

The magnetic anisotropy energy (MAE) of the bulk hcp Co under mechanical deformation is calculated by ab initio density functional theory (DFT) calculations based on the projector augmented wave method. We present a thorough investigation with respect to the choice of exchange-correlation functionals. The generalized gradient approximation (GGA) succeeds in predicting the easy axis of magnetization but underestimates the MAE in comparison to the experimental value, whereas the local density approximation gives a wrong magnetic easy axis. The DFT+U method offers an alternative to increase the MAE value. Unfortunately, as the MAE reaches the experimental value, strong distortions of the lattice parameters are observed. Our results with GGA suggest that a simultaneous reduction of the c/a ratio and increase of the lateral lattice parameter a will strongly enhance the MAE of the material, as observed experimentally. We also found that the MAE in hcp Co is reduced by shear strain.

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Articles
Copyright
Copyright © Materials Research Society 2013 

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References

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