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arXiv · 1012.4717

Magnetocrystalline anisotropy and uniaxiality of MnAs/GaAs(100) films

J. Magnus Wikberg·Ronny Knut·Sumanta Bhandary·Igor di Marco·Mikael Ottosson·Janusz Sadowski·Biplab Sanyal·Pål Palmgren·Cheuk W. Tai·Olle Eriksson·Olof Karis·Peter Svedlindh
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Abstract

We present an investigation of the magnetic behavior of epitaxial MnAs films grown on GaAs(100). We address the dependence of the magnetic moment, ferromagnetic transition temperature ($T_c$) and magnetocrystalline anisotropy constants on epitaxial conditions. From thorough structural and magnetic investigations, our findings indicate a more complex relationship between strain and magnetic properties in MnAs films than a simple stretch/compression of the unit cell axes. While a small increase is seen in the anisotropy constants the enhancement of the magnetic moment at saturation is significant. X-ray magnetic circular dichroism results show a behavior of the spin- and orbital-moment which is consistent with a structural transition at $T_c$. In particular, we find that the ratio of the orbital to spin moment shows a marked increase in the coexistence region of the ferromagnetic $\alpha$- and paramagnetic $\beta$-phases, a result that is well in accord with the observed increase of the $c/a$-ratio in the same temperature region. The \textit{ab initio} density functional calculations reveal that the magnetic properties are more sensitive towards change in in-plane axis as compared to a change of the out-of-plane axis, which is explained by the analysis of band structures. The effects of electron correlation in MnAs using \textit{ab initio} dynamical mean field theory are also presented.

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J. Magnus Wikberg, Ronny Knut, Sumanta Bhandary, Igor di Marco, Mikael Ottosson, Janusz Sadowski, Biplab Sanyal, Pål Palmgren, Cheuk W. Tai, Olle Eriksson, Olof Karis, Peter Svedlindh. 2010-12-21. Magnetocrystalline anisotropy and uniaxiality of MnAs/GaAs(100) films. https://arxiv.org/abs/1012.4717

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