Dresden 2017 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 2: Superconductivity: Properties and Electronic Structure 1
TT 2.11: Vortrag
Montag, 20. März 2017, 12:30–12:45, HSZ 103
Pressure-structure relationships in the 10 K layered carbide halide superconductor Y2C2I2 — •Kyunsoo Ahn1,2, Reinhard K. Kremer1, Arndt Simon1, and Alfonso Munoz3 — 1MPI for Solid State Research, Stuttgart, Germany — 2Department of Chemistry, Yonsei University, Wonju 220-710, Korea — 3Departamento de Física, Instituto de Materiales y Nanotecnología, and MALTA Consolider Team, Universidad de La Laguna, 38200 La Laguna, Tenerife, Spain
In order to investigate to what extend the superconducting and the structural properties of the 10 K layered yttrium carbide halide superconductor Y2C2I2 can be modified by external pressure we have studied the pressure dependence of the superconducting critical temperature and the crystal structure of Y2C2I2. Up to ∼2.5 GPa. We observe an increase of Tc from 10 K to about 12 K and a structural phase transition from a 1s to a 3s stacking variant. This occurs at ∼2.5 GPa above which Tc rapidly decreases to a value of ∼7.5 K at 7.5 GPa. Ab initio calculations corroborate the structural phase transition to occur at a critical cell volume of ∼270 Å3 corresponding to a pressure of ∼2.4 GPa, in good agreement with the experimental findings. The pressure dependence of Tc and inter-atomic distances and angles are discussed with respect to the electronic structure which is characterized by bands of low dispersion and narrow peak-valley features in the electronic density of states at the Fermi level.