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TT: Fachverband Tiefe Temperaturen

TT 34: Correlated Electrons: Metal-Insulator Transition 2

TT 34.4: Vortrag

Donnerstag, 28. Februar 2008, 14:45–15:00, H 2053

Interplay of electron-electron and electron-phonon interaction in the metal to insulator transition in vanadium oxides. — •Leonetta Baldassarre^1,2, Emanuele Arcangeletti¹, Andrea Perucchi¹, Daniele Nicoletti¹, Daniele Di Castro¹, Carlo Marini¹, Paolo Postorino¹, and Stefano Lupi¹ — ¹CNR-INFM COHERENTIA and Department of Physics, University of Rome ”La Sapienza” , Rome, Italy — ²Experimentalphysik II, Universität Augsburg, D-86135 Augsburg, Germany

Several families of vanadium oxides display metal to insulator transitions (MIT) often driven by both temperature (T) and pressure (P) with jumps of conductivity up to 7 orders of magnitude. While the transition in V₂O₃ is considered as induced mainly by electronic correlation (Mott-Hubbard transition), the MIT mechanism that drives the electronic transition in VO₂ is still unclear, probably determined by an interplay between electronic and lattice degrees of freedom.

Here we present a complete investigation of MIT as a function of T and P of V₂O₃ and VO₂. Infrared measurements have been performed in a wide range of T (10-600 K) and P (0-15 GPa) in order to cover the rich phase diagrams of those materials. P-dependent Raman measurements have also been performed on VO₂ so to follow also the lattice dynamics. Moreover, the high temperature incoherent phase is discussed in V₂O₃, the ideal playground to study the correlation effects on the low-energy electrodynamics.