Dresden 2020 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 41: Unconventional Superconductors

TT 41.13: Vortrag

Mittwoch, 18. März 2020, 18:30–18:45, HSZ 201

Low-Temperature Phase of the Cd2Re2O7 Superconductor: Ab initio Phonon Calculations and Raman Scattering — •Reinhard K. Kremer1, Konrad J. Kapcia2, Andrzej Ptok2, Przemysław Piekarz2, Fereidoon S. Razavi3, Maureen Reedyk3, Mojtaba Hajialamdari3, and Andrzej M. Oleś41MPI für Festkörperforschung, Stuttgart, Germany — 2Institute of Nuclear Physics, Polish Academy of Sciences, Kraków, Poland — 3Dep. of Physics, Brock University, St. Catharines, Canada — 4Marian Smoluchowski Institute of Physics, Jagiellonian University, Kraków, Poland

Using an ab initio approach, we report a phonon soft mode in the tetragonal structure described by the space group I4122 of the 1 K 5d superconductor Cd2Re2O7. It induces an orthorhombic distortion to a crystal structure described by the space group F222 which hosts the superconducting state. This new phase has a lower total energy than the other known crystal structures of Cd2Re2O7. Comprehensive temperature dependent Raman scattering experiments on isotope enriched samples, 116Cd2Re218O7, not only confirm the already known structural phase transitions but also allow us to identify a new characteristic temperature regime around ∼ 80 K, below which the Raman spectra undergo remarkable changes with the development of several sharp modes and mode splitting. Together with the results of the ab initio phonon calculations we take these observations as strong evidence for another phase transition to a novel low-temperature crystal structure of Cd2Re2O7.

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