Dynamic dislocation effects in low-temperature creep stimulated in β-tin single crystals by a superconducting transition

Low-temperature creep of high-purity beta-tin single crystals oriented for plastic slip in the system (100)<< 010 >> is studied. The experiments are performed in the temperature interval 0.5 < T < T-c, where T-c approximate to 3.7 K is the critical superconducting transition temperature. The samples were loaded above the yield stress and nonstationary creep was induced in them by using a magnetic field to induce a transition from the normal (N) into the superconducting (S) state. It is established that the time dependence of the post-NS-transition increase of deformation consists of three stages: transition, exponential, and logarithmic. A theory of creep is developed in the Appendix for a physical interpretation of these stages; the theory is based on the ideas of thermally activated, quantum (tunneling), and dynamic motion of dislocations in a Peierls potential relief taking account of their electronic and radiation drag. The particularities associated with the manifestation of the dynamical properties of the dislocation strings at the individual stages of creep are analyzed in detail. The transition of the samples into a superconducting state sharply decreases the electronic stopping of the dislocations and increases the contribution of the dynamic component of the dislocation flux to the creep rate. Comparing the experimental and theoretical results made it possible to obtain empirical values of some phenomenological parameters of the dislocations of the creep model.