Spin—Lattice Relaxation, Unstable Lattice Modes, and Critical Fluctuations

Abstract

The problem of the origin and nature of the critical divergences and fluctuations near second-order phase transitions remains one of the major unsolved problems in the physics of many-body systems. It seems that the characteristic form of the divergences is the same regardless of whether the transitions occur in a ferroelectric, a superconductor, a binary mixture, a fluid, or a ferro-magnet. In all these cases the order parameter describing the system exhibits large amplitude fluctuations which relax back to equilibrium ever more slowly as the critical point is approached.

Based in part on work performed under the auspices of the U.S. Atomic Energy Commission.

On leave of absence from Institute “J. Stefan”, University of Ljubljana, Ljubljana, Yugoslavia.