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Recent first-principles simulations of materials for electronic, spintronic and piezoelectric sensors applications will be reviewed with the emphasis on the description of effects due to magnetic and chemical disorder. Examples of predictive power of the modern alloy theory will be given, but challenges will be discussed as well. In particular, the origin of the anomalous, 400% increase of the piezoelectric coefficient in ScxAl1-xN alloys will be revealed, and a strategy for a systematic search for new materials with high piezoelectric response will be outlined [1]. Motivated by the need for strategies to engineer the magnetism of potentially half-metallic materials, such as NiMnSb, we perform a combined theoretical and experimental study of the phase stability and magnetism of the off-stoichiometric Ni1-xMn1+xSb in the half-Heusler crystal phase, and argue that a substitution of Ni for Mn should have a beneficial effect [2]. Using first-principles calculations we study the effect of magnetic disorder above the magnetic transition temperature on the structural and thermodynamic properties of CrN, a material which undergoes a structural transition from orthorhombic antiferromagnetic to cubic paramagnetic phase around room temperature. We suggest a technique for molecular dynamics simulations of paramagnetic phases. When magnetic disorder and strong electron correlations are taken into account simultaneously, pressure- and temperature-induced structural and magnetic transitions in CrN can be understood [3].
[1] F. Tasnadi, B. Alling, C. Höglund, G. Wingqvist, J. Birch, L. Hultman, and I. A. Abrikosov, Phys. Rev. Lett. 104, 137601 (2010). [2] M. Ekholm, P. Larsson, B. Alling, U. Helmersson, and I. A. Abrikosov, J. Appl. Phys. 108, 093712 (2010). [3] B. Alling, T. Marten, and I. A. Abrikosov, Nature Materials 9, (2010) 283; Phys. Rev. B 82, (2010) 184430; P. Steneteg, B. Alling, and I. A. Abrikosov, in preparation |
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