Berlin 2024 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 18: SrTiO3: A Versatile Material from Bulk Quantum Paraelectric to 2D Superconductor: Poster (joint session TT/KFM/MA/O)
KFM 18.1: Poster
Mittwoch, 20. März 2024, 15:00–18:00, Poster E
Optical conductivity of superconducting Nb:SrTiO3 in magnetic fields at GHz frequencies — •Cenk Beydeda1, Markus Thiemann1, Martin Dressel1, Hans Boschker2, Jochen Mannhart2, and Marc Scheffler1 — 11. Physikalisches Institut, Universität Stuttgart — 2Max-Planck-Institut für Festkörperforschung, Stuttgart
Doped SrTiO3 was among the first unconventional superconductors, the application of the BCS theory is questionable due to the small Fermi energy. Here we present the optical conductivity (1−30 GHz) of superconducting Nb:SrTiO3 in magnetic field. We observe features typical of an s-wave single-gap dirty type II superconductor. We attribute a kink in the magnetic field dependence to 2 distinct superconducting bands. We observe values of the real part of the optical conductivity exceeding the normal state value multiple times for rising magnetic field. Excessive losses at low frequency hf≪ 2Δ in dependence of temperature are a known feature of superconductivity and a result of coherence effects of the Cooper pairs in the superconducting state (coherence peak). The excessive losses we observe with rising magnetic field are substantially different from the coherence peak, especially in magnetic field dependence and absolute values. As far as we know, excessive losses of this type were not observed in any other superconductor. It is not clear whether Nb:SrTiO3 is the only material that can show excessive losses of this type. We present an interpretation of our data in terms of Caroli-de Gennes-Matricon modes in the vortex state, reproducing the effect of excessive losses qualitatively.
Keywords: Microwave; Optical conductivity; Superconductivity; Magnetic field; SrTiO3