Regensburg 2004 – scientific programme

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TT: Tiefe Temperaturen

TT 6: Niederdimensionale Systeme (incl. Peierls-Übergang, organische Leiter, ...)

TT 6.13: Talk

Monday, March 8, 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.