Multiple soft-mode vibrations of lead zirconate.

Polarized Raman, IR, and time-domain THz spectroscopy of orthorhombic lead zirconate single crystals have yielded a comprehensive picture of temperature-dependent quasiharmonic frequencies of its low-frequency phonon modes. It is argued that these modes primarily involve vibrations of Pb ions and librations of oxygen octahedra. Their relation to phonon modes of the parent cubic phase is proposed.

Equilibrium state of the mean-field Potts glass.

We investigate the low-temperature equilibrium state of the p-state mean-field Potts glass. It is the presently believed that there is a temperature interval T(2) < T < T(c) within which the equilibrium state for p > p(*) approximately 2.82 is described by the cavity method corresponding to the first level of replica-symmetry breaking.