Speakers: František Máca (Department of Condensed Matter Theory, Institute of Physics ASCR)
Place: Na Slovance, main lecture hall
Presented in English
Organisers:
Department of Condensed Matter Theory
Abstract:
We search by computational simulations for new materials which may be suitable for spintronics, both metallic and semiconducting magnetic compounds of manganese. In particular, we report on an ab-initio theoretical study based on the density functional theory to investigate the CuMn-V antiferromagnets and to explain a structural anisotropy observed in ferromagnetic (Ga,Mn)As epilayers.
Previous works showed low-temperature antiferromagnetism and semimetal electronic structure of the semi-Heusler CuMnSb. We show that the transition to a semiconductor-like band structure upon introducing the lighter group-V elements is present in both the metastable semi-Heusler and the stable orthorhombic crystal structures of CuMnAs and CuMnP [1]. We also predict a remarkable increase of the Néel temperature and a strong enhancement of magnetocrystalline anisotropy in the layered crystals of CuMnAs. The experimental results indeed indicate that the Néel temperature in CuMnAs is much higher than in CuMnSb.
Our full-potential density functional calculations explain the energetic preference of substitutional Mn to decorate the stacking faults in (Ga,Mn)As [2]. This preference energy is comparable with the formation energy of the faults in a pure GaAs. We surmise that the enhanced Mn density along the common [1-10] direction of the stacking fault planes represents the micro-structural origin of the in-plane uniaxial magnetocrystalline anisotropy of these semiconductors.
References:
[1] F. Máca et al, J. Magn. Magn. Mater. 324 (2012) 1606.
[2] M. Kopecký et al, Phys. Rev. B 83 (2011) 235324.
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