Presentation of the Ginzburg-Landau model

This work is done with Philippe Curty and Hans Beck  and with the following external collaborations:

• Hugo Fort (Uruguay)

• Xavier Bagnoud (Fribourg)

• Michael Dzierzawa  (Augsburg)

 

The following aspects are treated:

• The interplay between amplitude and phase fluctuations. 

 
• The possibility of a first order phase transition in the GL model. 

• The pseudogap observed in high Tc superconductors.

 
• A possible first order transition in high Tc superconductors.

• Bose-Einstein condensation.

• The role of order parameter fluctuations in the Nematic-Smectic A transition in liquid crystals.

 
Simulations of the 3d Ginzburg-Landau Model with Soft Amplitudes
Ph. Curty, H. Beck
(submitted)
   Using cluster Monte Carlo simulations, the 3d complex Ginzburg-Landau model reveals a first order transition when the amplitude $ | \psi | $ of the complex field $ \psi $ is sufficiently soft, i.e. adapts itself to the phase configurations of the field. This transition is driven by phase fluctuations in agreement with a previous analytical approach.

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First Order Transition in the Ginzburg-Landau Model, cond-mat/0008428
Ph. Curty, H. Beck
Phys. Rev. Lett.  85, 796 (2000)
   The d-dimensional complex Ginzburg-Landau (GL) model is solved according to a variational method by separating phase and amplitude. The GL transition becomes first order for high superfluid density because of effects of phase fluctuations. We discuss its origin with various arguments showing that, in particular for d = 3, the validity of our approach lies precisely in the first order domain.

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