A simple phenomenological model for characterizing the coupled effect of strain states and temperature on the normal-state electrical resistivity in Nb_3Sn superconductors

摘要

To establish a general scaling relation for the effects of strain tensor on the critical current density in Nb_3Sn, the normal-state transport properties of strained Nb_3Sn superconductors are invaluable, which are directly relevant to the superconducting state. The three-dimensional (3D) strain- and temperature-dependent electrical resistivity of Nb_3Sn in the normal state is explored, and a phenomenological model is suggested. The numerical simulation by the model proposed in this paper shows predicted normal state electrical resistance behavior, which in good agreement with the experimental data. Moreover, the dependence of the strain induced variation of the electrical resistivity of normal conducting Nb_3Sn on temperature with the largest change occurring at the temperature of 40 K (closer to the martensitic transformation temperature) can also be predicted. The model is helpful for identifying the scaling relation for the critical current density in the International Thermonuclear Experimental Reactor Nb_3Sn strands and understanding the origin of strain sensitivity in Nb_3Sn conductors.