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We review the recent developments in electronic Raman scattering measurements of charge nematic fluctuations in iron-based superconductors. A simple theoretical framework of a d -wave Pomeranchuk transition is proposed in order to capture the salient features of the spectra. We discuss the available Raman data in the normal state of 122 iron-based systems, particularly Co-doped BaFe 2 As 2 , and we show that the low-energy quasi-elastic peak, the extracted nematic susceptibility and the scattering rates are consistent with an electronic-driven structural phase transition. In the superconducting state with a full gap, the quasi-elastic peak transforms into a finite-frequency nematic resonance, evidences for which are particularly strong in the electron-doped systems. A crucial feature of the analysis is the fact that the electronic Raman signal is unaffected by the acoustic phonons. This makes Raman spectroscopy a unique probe of electronic nematicity. [ABSTRACT FROM AUTHOR]

Large glassy domains have been observed at 800 °C within the TeO2–TlF (from 7 to 65 mol% of TlF) and Tl2Te3O7–TlF (from 0 to 75 mol% of TlF content) systems. The density, glass transition and crystallisation temperatures of glassy samples have been determined. The main features of a structural evolution within the TlF–TeO2 glasses have been interpreted by analysing the relevant Raman spectra, and comparing them with those previously observed for the Tl2O-TeO2 system. [Copyright &y& Elsevier]