Nematic fluctuations and phase transitions in LaFeAsO: A Raman scattering study
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Raman scattering experiments on LaFeAsO with distinct antiferromagnetic (TAFM=140 K) and tetragonal-orthorhombic (TS=155 K) transitions show a quasielastic peak (QEP) in B2g symmetry (2 Fe tetragonal cell) that fades away below ∼TAFM 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 TS and TAFM in LaFeAsO compared to BaFe2As2 manifests itself in slower dynamics of nematic fluctuations in the former.
This article is published as Kaneko, U. F., P. F. Gomes, A. F. García-Flores, J-Q. Yan, T. A. Lograsso, G. E. Barberis, D. Vaknin, and E. Granado. "Nematic fluctuations and phase transitions in LaFeAsO: A Raman scattering study." Physical Review B 96, no. 1 (2017): 014506. DOI: 10.1103/PhysRevB.96.014506. Posted with permission.