arXiv subjects

W. Petry

Publications and source records attributed to W. Petry.

2 recordsLinked to original sources

arXiv2001

Calcium Rubidium Nitrate: Mode-Coupling $β$ Scaling without Factorization

The fast dynamics of viscous calcium rubidium nitrate is investigated by depolarized light scattering, neutron scattering and dielectric loss. Fast $β$ relaxation evolves as in calcium potassium nitrate. The dynamic susceptibilities can be described by the asymptotic scaling law of mode-coupling theory with a shape parameter $λ= 0.79$; the temperature dependence of the amplitudes extrapolates to $T_c\simeq 378$ K. However, the frequencies of the minima of the three different spectroscopies never coincide, in conflict with the factorization prediction, indicating that the true asymptotic regime is unreachable.

cond-mat.soft↗

arXiv2000

Vibrational States of Glassy and Crystalline Orthotherphenyl

Low-frequency vibrations of glassy and crystalline orthoterphenyl are studied by means of neutron scattering. Phonon dispersions are measured along the main axes of a single crystal, and the corresponding longitudinal and transversal sound velocities are obtained. For glassy and polycrystalline samples, a density of vibrational states is determined and cross-checked against other dynamic observables. In the crystal, low-lying zone-boundary modes lead to an excess over the Debye density of states. In the glass, the boson peak is located at even lower frequencies. With increasing temperature, both glass and crystal show anharmonicity.

cond-mat.stat-mech↗