Berlin 2015 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 52: Superconductivity: Fe-based Superconductors – FeSe and others

TT 52.9: Talk

Wednesday, March 18, 2015, 11:45–12:00, H 2053

Superconductivity in the layered iron-germanide YFe₂Ge₂ — Jiasheng Chen¹, Zhuo Feng², Yang Zou¹, Peter Logg¹, Giulio Lampronti³, and •Malte Grosche¹ — ¹Cavendish Laboratory, Cambridge UK — ²London Centre of Nanotechnology, University College, London UK — ³Dept. of Earth Sciences, Cambridge UK

In the d-electron system YFe₂Ge₂, an unusually high Sommerfeld ratio of the specific heat capacity C/T ∼ 100 mJ/(molK²) and a non Fermi-liquid temperature dependence of the electrical resistivity ρ ≃ ρ₀ + AT^3/2 signal strong electronic correlations in an anomalous metallic state. Full resistive transitions, DC diamagnetic screening fractions of up to 80% and clear heat capacity anomalies observed at the transition suggest that pure samples of YFe₂Ge₂ superconduct below 1.8 K [1]. Although the nominal Fe valence in YFe₂Ge₂ is the same as in the isostructural iron-arsenides (K/Rb/Cs)Fe₂As₂, which have similar superconducting transition temperatures and a similarly enhanced heat capacity as YFe₂Ge₂, DFT studies suggest that the electronic structure of YFe₂Ge₂ differs substantially from that of the iron-arsenide superconductors, motivating alternative scenarios [2].

[1] Y. Zou et al, Physica Status Solidi (RRL) 8, 928 (2014).

[2] A. Subedi, PRB 89 024504 (2014);

D. J. Singh, ibid. 024505 (2014).