Vortex creep and thermal depinning within strong pinning theory

Vortex pinning in type-II superconductors can occur through the collective action of many pins (weak collective pinning scenario) or through plastic deformations induced by a low density of defects (strong pinning scenario). For the latter case, a new formalism has recently be developed [1-4] to provide a quantitative link between the microscopic pinning landscape and experimentally accessible quantities describing pinning on a macroscopic level. Examples are the critical current density $j_c$, the $I$-$V$ characteristics, or the $ac$ Campbell length $\lambda_C$. Inspired by the original work of Larkin and Brazovskii [5,6] on density wave pinning, we have extended the strong pinning formalism to account for thermal depinning of flux lines and vortex creep. [1] G. Blatter, V. B. Geshkenbein, and J. A. G. Koopmann, Phys. Rev. Lett. {\bf 92}, 067009 (2004). [2] A. U. Thomann, V. B. Geshkenbein, and G. Blatter, Phys. Rev. Lett. {\bf 108}, 217001 (2012). [3] R. Willa, V. B. Geshkenbein, and G. Blatter, Phys. Rev. B {\bf 92}, 134501 (2015). [4] R. Willa, V. B. Geshkenbein, R. Prozorov and G. Blatter, Phys. Rev. Lett. (in press). [5] A. Larkin and S. Brazovskii, Solid State Communications {\bf 93}, 275 (1995). [6] S. Brazovskii and A. Larkin, Synthetic Metals {\bf 86}, 2223 (1997).