Berlin 2005 – scientific programme
Parts | Days | Selection | Search | Downloads | Help
TT: Tiefe Temperaturen
TT 2: Correlated Electrons - Metal Insulator Transition
TT 2.7: Talk
Friday, March 4, 2005, 11:45–12:00, TU H2053
Local Structure of V2O3 in the vicinity of the metal-insulator transition — •P. Pfalzer1, M. Klemm1, M. L. denBoer2 und S. Horn1 — 1Universität Augsburg, Lehrstuhl für Experimentalphysik II, Universitätsstr. 1, 86135 Augsburg — 2Queens College of CUNY, 65-30 Kissena Blvd., Flushing, New York 11367, USA
We have measured the temperature dependence of the local structure of V2O3 close to the metal-insulator transition (MIT). Polarization dependent EXAFS-measurements give evidence that the emergence of the insulating state is directly connected to the trigonal distortion of the O coordination octahedra, which is determined by the distance of the V atoms along the hexagonal c-axis. While this V-V pair-distance shows a sharp jump exactly at the temperature of the MIT, the properties of the Vanadium bonds in the a-b (basal-)plane are smeared out and no abrupt changes are detected at the MIT. Even in the metallic phase the full trigonal symmetry is not recovered, but a local monoclinic distortion — although significantly reduced in size — persists up to room temperature. This suggests that the driving forces for the MIT are due to interactions between V ions in the basal plane, leading to the insulating state e.g. via changes in hybridization.