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TT: Fachverband Tiefe Temperaturen
TT 2: Superconductivity: Sample Preparation, Characterization, Properties and Electronic Structure
TT 2.10: Vortrag
Montag, 16. März 2020, 12:00–12:15, HSZ 103
Evidence for an orbital dependent Mott transition in the ladders of (La, Ca)xSr14−xCu24O41 derived by electron energy-loss spectroscopy — •Friedrich Roth1, Udo Ammerahl2, Alexandre Revcolevschi2, Bernd Büchner3, Martin Knupfer3, and Jörg Fink3,4,5 — 1Institute of Experimental Physics, TU Bergakademie Freiberg, Leipziger Straße 23, D-09599 Freiberg, Germany — 2Laboratoire de Physico-Chimie de l’État Solide, Université Paris-Sud, 91405 Orsay, France — 3IFW Dresden, P.O. Box 270116, D-01171 Dresden, Germany — 4Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany — 5Institute for Solid-State and Material Physics, Technical University Dresden, D-01062 Dresden, Germany
The knowledge of the charge carrier distribution among the different orbitals of Cu and O is a precondition for the understanding of the physical properties of various Cu-O frameworks. We employ electron energy-loss spectroscopy to elucidate the charge carrier plasmon dispersion in (La, Ca)xSr14−xCu24O41 in dependency of x as well as temperature. We observe that the energy of the plasmon increases upon increasing Ca content, which signals an internal charge redistribution between the two Cu-O subsystems. Moreover, a comparison of the experimental plasmon excitations with RPA-like calculations indicates that the holes which are transferred to the Cu2O3 ladders are mainly located on O orbitals in the rungs and to a much lesser extent in those in the legs. This is related to a different filling of the bonding and antibonding band leading to an orbital dependent Mott transition.