Dresden 2017 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 19: Poster Session: Correlated Electrons 1
TT 19.48: Poster
Montag, 20. März 2017, 15:00–19:00, P2-EG
Crystal structure determination of Ti-doped Ca2RuO4 — •Sebastian Hoffmann, Stefan Kunkemöller, Kevin Jenni, and Markus Braden — II. Physikalisches Institut, Universität zu Köln, Zülpicher Straße 77, D-50937 Köln, Germany
The crystal structure of 0, 1 and 10% Ti-doped Ca2RuO4 was determined by single crystal X-ray diffraction at 100K and 300K. To clarify the mechanism of superconductivity in Sr2RuO4, the phase diagram of Ca2−xSrxRuO4 was analysed, which possesses ferromagnetism, anitferromagnetism, superconductivity, orbital ordering and metal-insulator transitions. Sr2RuO4 is isostructural to the ideal tetragonal K2NiF4 structure with spacegroup I4/mmm and non-distorted NiF6-octahedra. The Mott insulator Ca2RuO4 crystallizes in the orthorhombic spacegroup Pbca, in which the RuO6-octahedra are highly distorted. Upon cooling, structural changes lead to effects like the anomalous elongation of the b-lattice constant and to a shortening of the a- and c-lattice constant. These changes are accompanied by a flattening, rotation and tilting of the RuO6-octahedra, with the tilt occuring around the b-lattice constant. In Ca2RuO4 there seems to be a connection of the magnetic ordering at low temperatures and the structural behaviour. Upon cooling below 110K, where antiferromagnetic order sets in, the elongation of the b-lattice constant saturates. Ti doping up to 10% seems to change the elongation from b(300K)−b(TN) = 0.1643Å down to 0.0898Å. For the Ti-doped samples, the anomalous properties of Ca2RuO4 (relative to Sr2RuO4) are thus attenuated.