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arXiv · 0903.2430

The nature of the magnetic and structural phase transitions in BaFe$_{2}$As$_{2}$

Stephen D. Wilson·Z. Yamani·C. R. Rotundu·B. Freelon·E. Bourret-Courchesne·R. J. Birgeneau
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Abstract

We present the results of an investigation of both the magnetic and structural phase transitions in a high quality single crystalline sample of the undoped, iron pnictide compound BaFe$_2$As$_2$. Both phase transitions are characterized via neutron diffraction measurements which reveal simultaneous, continuous magnetic and structural orderings with no evidence of hysteresis, consistent with a single second order phase transition. The onset of long-range antiferromagnetic order can be described by a simple power law dependence $ϕ(T)^2\propto(1-\frac{T}{T_N})^{2β}$ with $β=0.103\pm0.018$; a value near the $β=0.125$ expected for a two-dimensional Ising system. Biquadratic coupling between the structural and magnetic order parameters is also inferred along with evidence of three-dimensional critical scattering in this system.

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Stephen D. Wilson, Z. Yamani, C. R. Rotundu, B. Freelon, E. Bourret-Courchesne, R. J. Birgeneau. 2009-06-05. The nature of the magnetic and structural phase transitions in BaFe$_{2}$As$_{2}$. https://doi.org/10.1103/physrevb.79.184519

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