Berlin 2018 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 110: Superconductivity: Fe-based Superconductors - 1111 and Others

TT 110.7: Vortrag

Freitag, 16. März 2018, 11:15–11:30, H 3010

Unconventional Superconductivity in Poly- and Single Crystal YFe₂Ge₂ — •Jiasheng Chen¹, Konstantin Semeniuk¹, Monika Gamza², and Malte Grosche¹ — ¹Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, UK — ²Jeremiah Horrocks Institute for Mathematics, Physics and Astrophysics, University of Central Lancashire, Preston PR1 2HE, UK

The d-electron system YFe₂Ge₂ exhibits an unusually high Sommerfeld coefficient C/T ∼ 100 mJ/(molK²) at low temperatures, indicative of strong electronic correlations. Although superconductivity in YFe₂Ge₂ has been widely observed in electrical measurements below 1.8 K, it is strongly sample-dependent and fragile against disorders [1, 2]. Until now, thermodynamic signatures of bulk superconducting transitions have only been reported in polycrystals with residual resistance ratios (RRR) above 70 [2], but not in single crystals. Detail studies on the structures and electrical properties of polycrystals with varying nominal compositions have shed light on the origins of this strong sample dependence. It also led to our success in producing a new generation of single-crystal YFe₂Ge₂ with RRR reaching ∼ 170 which shows bulk superconductivity as seen in high quality polycrystals. This thus allows for further investigations into the nature of its apparently unconventional superconductivity by means of heat capacity, penetration depth and quantum oscillation measurements.
Y. Zou et al., Physica Status Solidi - Rapid Research Letters 8, 928 (2014),
H. Kim et al., Philos Mag 95, 804 (2015).
J. Chen et al., PRL 116, 127001 (2016)