High-temperature change of the creep rate in YBa 2Cu3O 7-delta films with different pinning landscapes

N. HABERKORN; M. MIURA; J. BACA; B. MAIOROV; I. USOV; P. DOWDEN; S. R. FOLTYN; T. G. HOLESINGER; J. O. WILLIS; K. R. MARKEN; T. IZUMI; Y. SHIOHARA; L. CIVALE

PHYSICAL REVIEW B - CONDENSED MATTER AND MATERIALS PHYSICS

American Physical Society

Año: 2012 vol. 85 p. 174504 - 174511

0163-1829

Magnetic relaxation measurements in YBa2Cu3O7-d (YBCO) films at intermediates and high temperatures show that the collective vortex creep based on the elastic motion of the vortex lattice has a crossover to fast creep that significantly reduces the superconducting critical current density (Jc). This crossover occurs at temperatures much lower than the irreversibility field line. Westudy the influence of different kinds of crystalline defects, such as nanorods, twin boundaries and nanoparticles, on the high temperature vortex phase diagram of YBCO films. We found that the magnetization relaxation data is a fundamental tool to understand the pinning at high temperatures. The results indicates that high Jc values are directly associated with small creep rates. Based on the analysis of the depinning temperature in films with columnar defects, our results indicate that the size of the defects is the relevant parameter that determines thermal depinning at high temperatures. Also the extension of the collective creep regime depends on the density of the pinning centers.