Regensburg 2004 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 6: Niederdimensionale Systeme (incl. Peierls-Übergang, organische Leiter, ...)
TT 6.13: Vortrag
Montag, 8. März 2004, 17:15–17:30, H18
Dynamics of density waves in the incommensurate high field phase of CuGeO3. — •Klaus Kiefer1 and Mechthild Enderle2 — 1Technische Physik, Universität des Saarlandes, 66123 Saarbrücken — 2Institut Laue-Langevin, BP 156, Grenoble, 38042, France
The non magnetic, uniformly dimerized spin-Peierls ground state of a one-dimensional spin 1/2 Heisenberg antiferromagnet becomes instable at high magnetic fields. Above a critical magnetic field, incommensurate quantum fluctuations condensate into a ground state and form a static modulation pattern with both structural and magnetic components. The periodicity of this combined structural and spin density wave changes on variation of the external magnetic field, forcing the density wave to travel through the crystal lattice. However, the motion of the density wave is hindered by crystal defects. This leads to non-equilibrium states and in consequence to heat dissipation. The dynamics of the density wave in the presence of pinning centers can therefore be determined by the measurement of the dissipated heat. In the high field phase of CuGeO3 we observe the complete dynamic phase diagram of densitiy waves in dependence of driving force and temperature, including the solid pinned, the fluid drifting and the solid drifting state.