Observation of lattice softening at $T_{\mathrm{c}}$ in the FeSe${}_{0.5}$Te${}_{0.5}$ superconductor

Abstract

Polycrystalline samples of FeSe${}_{0.5}$Te${}_{0.5}$ were synthesized using a conventional solid-state reaction method. The onset of bulk superconductivity transition was confirmed by SQUID magnetometry at 12.5~K. ${}^{57}$Fe Mössbauer spectra in transmission geometry were recorded at temperatures between 6.0 and 320 K. Both the isomer shift and the total absorption started to drop about $T_c$, indicating a softening of the lattice. The drop is estimated to correspond to at least 60~K from the original Debye temperature ${\theta }_{\mathrm{D}}\approx 460$~K. Seebeck measurements indicate that the samples are $n$-type conductors at low temperatures with a cross-over to $p$-type conductivity around 135 K. The zero Seebeck coefficient is seen below $10.6$~K.

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Cited by in corpus (7)

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• Microstructural and transport properties of superconducting FeTe0.65Se0.35 crystals
• Electric field gradient wave (EFGW) in iron-based superconductor Ba(0.6)K(0.4)Fe2As2 studied by Mössbauer spectroscopy
• 57Fe Mossbauer study of Lu2Fe3Si5 iron silicide superconductor
• Phonon Spectra in the Parent Superconducting Iron-tuned Telluride Fe${}_{1+x}$Te from Inelastic Neutron Scattering and Ab Initio Calculations