Possible disordered ground states for layered solids and their diffraction patterns

Publisher Website
Google Scholar
Abstract
It has recently been shown, assuming only certain (physical) symmetries of the Hamiltonian, that one-dimensional Ising problems can have degenerate, disordered ground states (GS’s). This result is of interest since it implies a weak violation of the third law of thermodynamics. The ground-state disorder is, however, of a special kind, consisting of arbitrary mixtures of a short-period structure and its symmetry-degenerate partner or partners. In this study, we address the question of how this constrained disorder may appear in an experimentally accessible signal, namely, the diffraction pattern. To calculate the latter, we assume (as is commonly done with known polytypes) that the Ising Hamiltonian represents the energetics of stacking of close-packed layers of some hypothetical polytypic material. We then calculate the diffraction patterns along the stacking direction for the various possible kinds of disordered GS’s. We find that some disordered GS’s give diffraction patterns which are only weakly distinguished from their periodic counterparts, while in others the long-ranged correlations among the layers is destroyed by the disorder, giving a diffraction spectrum which is purely continuous. © 1996 The American Physical Society.
All Related Versions

This publication has 16 references indexed in Scilit: