THz spectroscopy is used to identify a broad distribution of two-level systems, characteristic of glasses, in the substitutional monatomic mixed crystal systems, Ba1-xCaxF2 and Pb1-xCaxF2. In these minimally disordered systems, two-level behavior, which was not previously known to occur, begins at a specific CaF2 concentration. The concentration dependence, successfully modeled using the statistics of the impurity distribution in the lattice, points to a collective dopant tunneling mechanism.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)