Dirty, Skewed, and Backwards: The Smectic AA-CC Phase Transition in Aerogel

We study the smectic AC transition in anisotropic and uniaxial disordered environments, e.g., aerogel with an external field. We find very strange behavior of translational correlations: the low-temperature, lower-symmetry Smectic C phase is itless translationally ordered than the it high-temperature, higher-symmetry Smectic A phase, with short-ranged and algebraic translational correlations, respectively. Specifically, the A and C phase belong to the quasi-long-ranged translationally ordered " XY Bragg glass '' and short-ranged translationally ordered " m=1 Bragg glass '' phase, respectively. The AC phase transition itself belongs to a new universality class, whose fixed points and exponents we find in a d=5-epsilon expansion

Electron and phonon correlations in systems of one-dimensional electrons coupled to phonons

Electron and phonon correlations in systems of one-dimensional electrons coupled to phonons are studied at low temperatures by emphasizing on the effect of electron-phonon backward scattering. It is found that the $2k_F$-wave components of the electron density and phonon displacement field share the same correlations. Both correlations are quasi-long-ranged for a single conducting chain coupled to one-dimensional or three-dimensional phonons, and they are long-ranged for repulsive electron-electron interactions for a three-dimensional array of parallel one-dimensional conducting chains coupled to three-dimensional phonons