Magnetic anisotropy in Ni2MnGa
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© 2002 American Physical Society (APS). This is the accepted version of the following article: Enkovaara, J. & Ayuela, A. & Nordström, L. & Nieminen, Risto M. 2002. Magnetic anisotropy in Ni2MnGa. Physical Review B. Volume 65, Issue 13. 134422/1-7. ISSN 1550-235X (electronic). DOI: 10.1103/physrevb.65.134422, which has been published in final form at http://journals.aps.org/prb/abstract/10.1103/PhysRevB.65.134422.
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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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Date
2002
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en
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134422/1-7
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Physical Review B, Volume 65, Issue 13
Abstract
We study here, within the density-functional theory, the magnetic anisotropy energy (MAE) in Ni2MnGa which is a prototype of a magnetic shape-memory alloy. We calculate the MAE, which is a key property for the magnetic shape-memory effect, for tetragonal structure with different ratios of the c and a lattice constants, reproducing the experimental easy axes both in compression and elongation of the structure. Good agreement between the theory and the experiments in the actual values of the MAE is also found when the nonstoichiometry of the experimental samples is modeled with a simple rigid band approximation. In addition, we estimate the magnetostriction coefficient, confirming the difference between the ordinary magnetostriction and the magnetic shape-memory effect. Equally important, we study the microscopic origin of the MAE in Ni2MnGa with the spin density and the orbital moment anisotropy and extend the analysis of the orbital moment anisotropy to the ternary compounds. These results show that the largest contribution to the MAE comes from Ni, in spite of the larger magnetic moment in the Mn sites.Description
Keywords
Ni2MnGa, magnetic anisotropy energy
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Citation
Enkovaara, J. & Ayuela, A. & Nordström, L. & Nieminen, Risto M. 2002. Magnetic anisotropy in Ni2MnGa. Physical Review B. Volume 65, Issue 13. 134422/1-7. ISSN 1550-235X (electronic). DOI: 10.1103/physrevb.65.134422.