Berlin 2018 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 3: Superconductivity: Properties and Electronic Structure I
TT 3.11: Vortrag
Montag, 12. März 2018, 12:15–12:30, H 0110
Terahertz and infrared spectroscopic study of in-gap excitations in epitaxial DyBa2Cu3O7 superconducting films — •Robert Dawson, Timofei Larkin, Daniel Putzky, Georg Christiani, Gennady Logvenov, Alexander Boris, and Bernhard Keimer — Max Planck Institute for Solid State Research, D-70569 Stuttgart, Germany
Investigations of the electronic ground state properties of high-temperature cuprate superconductors have revealed a complex array of competing forms of order, suggesting the existence of dipole-active excitations at low energies which evolve across a wide range of doping levels. Unfortunately, the strong optical response of the superconducting condensate below Tc masks low energy spectral features and makes their direct measurement challenging. To address this issue we have combined the three complementary phase-sensitive techniques of millimeter-wave interferometry, high-resolution time domain terahertz spectroscopy, and infrared ellipsometry to sensitively probe the in-gap states of DyBa2Cu3O7 epitaxial films grown by atomic-layer-by-layer oxide MBE. We have obtained the continuous complex dielectric function in the spectral range of 0.5meV to 0.5eV and have observed its evolution as a function of temperature between 7K and 300K. We observe significant spectral weight accumulation at frequencies below 500GHz in the superconducting state, with 30% of the total charge carrier density remaining uncondensed even at temperatures below Tc/10. We will discuss this result and its implications for the evolution of the spectral weight distribution in the DBCO-1237 compound.