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-xCaₓF₂ and Pb_1-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.
No takes yet. Share an insight, caveat, or question.
Wrubel et al. (2006) studied this question.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: