Comparison of Flux Pinning Mechanism in Laser Ablated YBCO and YBCO:BaZrO3 Nanocomposite Thin Films
Thin films of YBCO and YBCO:BaZrO3 (BZO) nanocomposite have been deposited using the pulsed laser deposition technique. Substantial increase in critical current density (J C ) and pinning force density (F p ) of the nanocomposite thin films was observed. The possible pinning mechanism in YBCO:BZO nanocomposite thin films has been explored and compared with the pinning mechanism in pure YBCO thin film by studying the variation of J C with magnetic field (B) and temperature. In the intermediate field regime (0.1–1 T), J C follows B −α with nearly similar values of α for YBCO and YBCO:BZO nanocomposite thin films indicating similar pinning mechanism in both thin films. The variation of J C with reduced temperature (t=T/T C ) has been studied for both the films and it was observed that the mechanism of pinning in both YBCO and YBCO:BZO thin films is similar (δT C pinning). The observed enhanced values of J C and F p of the nanocomposite thin film is attributed to the presence of BZO nanoparticles, which induces more defects due to lattice mismatch between YBCO and BZO leading to improved flux pinning properties of the nanocomposite thin film.
KeywordsYBCO Nanocomposite Critical currents Vortex pinning
The authors are thankful to Prof. A.K. Grover (TIFR, India) for useful discussion and for the use of MPMS SQUID VSM. The authors also acknowledge the support received in INUP Program at CEN, IIT Bombay which have been sponsored by DIT, MCIT, Government of India through which part of the reported work was carried out. One of us (AKJ) is thankful to CSIR, New Delhi, India for the award of Senior Research Fellowship. Financial support from BRNS, India is also gratefully acknowledged.