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arXiv · 1702.03774

Nematic Fluctuations and Phase Transitions in LaFeAsO: a Raman Scattering Study

U. F. Kaneko·P. F. Gomes·A. F. Garcia-Flores·J. Q. Yan·T. A. Lograsso·G. E. Barberis·D. Vaknin·E. Granado
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Abstract

Raman scattering experiments on LaFeAsO with splitted antiferromagnetic (T_AFM = 140 K) and tetragonal-orthorhombic (T_S = 155 K) transitions show a quasi-elastic peak (QEP) in B2g symmetry (2 Fe tetragonal cell) that fades away below ~T_AFM and is ascribed to electronic nematic fluctuations. A scaling of the reported shear modulus with the T-dependence of the QEP height rather than the QEP area indicates that magnetic degrees of freedom drive the structural transition. The large separation between T_S and T_AFM in LaFeAsO compared with their coincidence in BaFe2As2 manifests itself in slower dynamics of nematic fluctuations in the former.

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U. F. Kaneko, P. F. Gomes, A. F. Garcia-Flores, J. Q. Yan, T. A. Lograsso, G. E. Barberis, D. Vaknin, E. Granado. 2017-02-13. Nematic Fluctuations and Phase Transitions in LaFeAsO: a Raman Scattering Study. https://doi.org/10.1103/physrevb.96.014506

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