Abstract
Internal friction (IF) measurements of epitaxial YBa2Cu3O7−x and Bi2Sr2CaCu2O8+δ thin films were carried out in magnetic fields up to 2.8 T. By measuring at constant temperature and magnetic fields applied perpendicular to the crystallographic c axis the lower critical field Hc1⊥ for the YBa2Cu3O7−x films was determined. For all film thicknesses between 43 nm and 600 nm values of 25 ± 3 mT at 20 K and 14 ± 3 mT at 50 K were found.For the Bi2Sr2CaCu2O8+δ films the IF was measured as a function of temperature for constant magnetic field H. For both H ⊥ c and H ∥ c a maximum in the IF was found which can be quantitatively explained within the model of thermally activated flux diffusion. The activation energy for the diffusion varies as H−0.3 for H ⊥ c and H−0.9 for H ∥ c.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
