arXiv subjects

N. I. Agladze

Publications and source records attributed to N. I. Agladze.

2 recordsLinked to original sources

arXiv2009

Intrinsic Localized Modes Observed in the High Temperature Vibrational Spectrum of NaI

Inelastic neutron measurements of the high-temperature lattice excitations in NaI show that in thermal equilibrium at 555 K an intrinsic mode, localized in three dimensions, occurs at a single frequency near the center of the spectral phonon gap, polarized along [111]. At higher temperatures the intrinsic localized mode gains intensity. Higher energy inelastic neutron and x-ray scattering measurements on a room-temperature NaI crystal indicate that the creation energy of the ground state of the intrinsic localized mode is 299 meV.

cond-mat.str-el↗

arXiv2005

Glass-like two-level systems in minimally disordered mixed crystals

THz spectroscopy is used to identify a broad distribution of two-level systems, characteristic of glasses, in the substitutional monatomic mixed crystal systems, Ba_{1-x}Ca_xF_2 and Pb_{1-x}Ca_xF_2. In these minimally disordered systems, two-level behavior begins at a specific CaF_2 concentration. The concentration dependence, successfully modeled using the statistics of the impurity distribution in the lattice, points to a collective dopant tunneling mechanism.

cond-mat.dis-nn↗