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arXiv · 1004.4328

Magneto-structural coupling and harmonic lattice dynamics in CaFe$_2$As$_2$ probed by Mössbauer spectroscopy

Zhiwei Li·Xiaoming Ma·Hua Pang·Fashen Li
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Abstract

In this paper we present detailed Mössbauer spectroscopy study of structural and magnetic properties of the undoped parent compound CaFe$_2$As$_2$ single crystal. By fitting the temperature dependence of the hyperfine magnetic field we show that the magneto-structural phase transition is clearly first-order in nature and we also deduced the compressibility of our sample to be $1.67\times10^{-2}\,GPa^{-1}$. Within the Landau's theory of phase transition, we further argue that the observed phase transition may stem from the strong magneto-structural coupling effect. Temperature dependence of the Lamb-Mössbauer factor show that the paramagnetic phase and the antiferromagnetic phase exhibit similar lattice dynamics in high frequency modes with very close Debye temperatures, $Θ_D \sim$270\,K.

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Zhiwei Li, Xiaoming Ma, Hua Pang, Fashen Li. 2011-05-29. Magneto-structural coupling and harmonic lattice dynamics in CaFe$_2$As$_2$ probed by Mössbauer spectroscopy. https://doi.org/10.1088/0953-8984%2F23%2F25%2F255701

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