NONEQUILIBRIUM THERMODYNAMICS OF NONISOTHERMAL ACTIVATION - ESCAPE OVER MESOSCOPIC BARRIERS .2. THE ESCAPE RATE

In the preceding article (I) it is argued that in noisy "macroscopic" systems (e.g. Josephson junctions) the effective potential for the pertinent degree of freedom (e.g. the magnetic flux) generally depends on the specimen's - local - temperature and, hence, that it should be given a thermodynamical (rather than the usual mechanical) significance. The ensuing nonequilibrium thermodynamics fluctuation theory is a generalization of Kramers' model of Brownian motion. In the present article (II) the novel theory is applied to nonisothermal activation effects. The influence of a finite heat capacity and limited heat exchange (with a "superbath", e.g. the helium reservoir) on the escape rate from a metastable state across a temperature dependent barrier is investigated. Inter alia it is shown that for a thermally isolated activation process the pertinent entropy barrier may be much higher than the usual isothermal Gibbs barrier.