Regensburg 2002 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 22: Postersitzung III: Syst. korr. Elektr.: Theorie II (1-15), Metall-Isol.- und Phasenüberg
änge (16-33), SL: Massivmat., Bandl., Pinning, Vortexdyn., Transport, Korngr. (34-43), Niedrigdim. Syst., Magnetotransport (44-63)

TT 22.25: Poster

Donnerstag, 14. März 2002, 14:00–17:30, A

Optically induced transient conductivity in the charge density system K0.3MoO3 — •I. Dotsenko1, B. Beschoten1, P. van Loostrecht2, G. Güntherodt1, and S. van Smaalen31II. Physikalisches Institut RWTH Aachen — 2Materials Science Center University of Groningen — 3Lehrstuhl für Kristallographie Universität Bayreuth

We investigate the transient optically induced conductivity in quasi-one dimensional blue-bronze (K0.3MoO3) single crystals after infrared excitation. This system exhibits a charge density wave (CDW) phase transition at 180 K accompanied by a metal-insulator transition.

At low temperatures with the increasing current three distinct regimes in the electrical DC conductivity are identified. At low electrical fields the CDW is pinned to the lattice and conduction only occurs through quasi-particle excitations. With increasing field the conduction becomes highly non-linear. In the third regime there is an onset of negative differential conductivity.

We investigated transient changes of the conductivity in all regimes after impulsive excitation by FIR light from the FELIX free electron laser. The excitation frequency was tuned to that of the phase phonon. Multicomponent behaviour of the conductivity is observed. The possibility of the CDW depinning at low fields is shown. Coherent oscillations of the sample electrical response in the non-linear regime indicate optically induced phase locking of the CDW condensate.

Work was supported by DFG/SPP 1073.

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