Thermally activated transport of a dislocation loop within an elastic model

We report thermally activated transport of a dislocation loop in terms of a line tension model, where the dislocation line is assumed to be a flexible string. According to conventional rate theory, the features of thermal activation are determined by the saddle-point geometry in high dimensional configuration space. If the circumference of a dislocation loop L is longer than a critical length L_c, the selected saddle-point configuration is the well known double-kink type solution. On the other hand, the manner of the thermal activation of a dislocation loop shorter than L_c is rather point-defect-like. In the present work, we pay attention to the temperature dependence of transition rate which is represented such as ν₀^* exp (- E / k_B T). The pre-exponential factor depends on temperature like ν₀^* ∼ T^{- 1 / 2} for sufficiently long dislocation loops on the basis of the analysis.