Regensburg 2007 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
TT: Fachverband Tiefe Temperaturen
TT 22: Low-dimensional Systems - Materials
TT 22.1: Vortrag
Donnerstag, 29. März 2007, 09:30–09:45, H18
Doping effects in the low-dimensional spin-Peierls system TiOCl — •Sebastian Glawion1, Götz Berner1, Matthias Schlachter1, Michael Sing1, Markus Hoinkis2, and Ralph Claessen1 — 1Experimentelle Physik 4 and Röntgen Research Center for Complex Materials, Universität Würzburg, D-97074 Würzburg, Germany — 2Experimentalphysik II, Universität Augsburg, D-86135 Augsburg, Germany
Due to the underlying triangular mesh of Ti atoms, which favours magnetic frustration, it has been speculated that the Mott-insulator TiOCl could show RVB-like superconductivity, provided one can induce metallic behaviour. However, the observed non-canonical transition into a dimerized spin-Peierls phase at Tc1=67K and a Bonner-Fisher-like susceptibility above Tc2=92K point to a quasi-1D behaviour discarding such frustrations. Interestingly, as was indicated, e.g., by ARPES, 2D magnetic frustrations nevertheless might be important due to a small but non-negligible interchain coupling. Searching for a metallic phase, we investigated the feasibility of doping in different ways: in situ evaporation of alkaline atoms and compositional variation by ion bombardment. We found that there are qualitative differences between the two methods, such that in the latter case the near Ef spectral weight remains essentially unchanged while the onset of its leading edge is aligned with the chemical potential, and the dispersion is lost. On the other hand, a new feature appears in the gap region upon alkaline intercalation. The overall Ti 3d dispersions are retained but the gap is not fully closed.