Large-n -limit model for quantum structural phase transitions with correlated random fields
Abstract
The effects of uncorrelated and correlated random fields on the critical properties in the quantum displacive limit in systems undergoing structural phase transitions are investigated within the Hartree approximation. An unusual critical behavior, absent dimensional reduction, and breaking of the scaling exponent relations, occurs as a competition of thermal, quantum, and random field fluctuations when the transition is driven by the temperature. On the contrary, by our approaching the quantum displacive limit in terms of the interaction-strength parameter a picture emerges which is consistent with recent renormalization-group predictions. In particular the dimensional reduction is present also for long-range interactions and correlated random fields due to the absence of perturbative effects as the Griffiths singularities which disappear in the large-n limit.
- Publication:
-
Physical Review B
- Pub Date:
- March 1987
- DOI:
- 10.1103/PhysRevB.35.3536
- Bibcode:
- 1987PhRvB..35.3536B
- Keywords:
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- 64.60.-i;
- General studies of phase transitions