Transport studies of YBa2Cu3Oy/YxPr 1-xBa2Cu3Oy and YBa2Cu3Oy/R0.7M 0-3MnO3 superlattices, in which R = La or Nd, and M = Ca or Sr
Journal
Journal of Physics and Chemistry of Solids
Journal Volume
62
Journal Issue
9-10
Pages
1837-1846
Date Issued
2001
Author(s)
Abstract
We report the transport studies of YBa2Cu3Oy/YxPr 1-xBa2Cu3Oy and YBa2Cu3Oy/R1-xMxMnO 3 superlattices in magnetic fields in which R = La or Nd, and M = Ca or Sr. The X-ray diffraction of samples shows superlattice structure. The resistive transition in a magnetic field shows thermal activated behavior. The flux pinning is reduced when the coupling strength between YBCO layers is decreased. The angular dependence of the critical current of YBa2Cu3Oy/PrBa2Cu 3Oy superlattices reveals the dimensionality of superlattices. The magnetoresistance ratio (MR),|Δρ(H = 7 T) - Δρ(H = 0)|/Δρ(H = 7 T), of YBa2Cu3Oy/R1-xM xMnO3 superlattices is affected by the layer coupling of R1-xMxMnO3 layers. The enhancement of the MR ratio in the tri-layer YBa2Cu3Oy/La0.7M 0.3MnO3/YBa2Cu3Oy film in the low temperature regime is significant and has a value of 33650% at T = 75 K. We attribute this enhancement of the MR to the ordering of magnetic moment in ferromagnetic layers in magnetic fields. The results are discussed in terms of existing theories. © 2001 Elsevier Science Ltd. All rights reserved.
Other Subjects
Critical current density (superconductivity); Crystal structure; Electric conductivity; Ferromagnetism; Magnetic couplings; Magnetic field effects; Magnetic flux; Magnetic moments; Magnetoresistance; Superconducting transition temperature; Thermal effects; Thin films; Transport properties; X ray diffraction analysis; Yttrium barium copper oxides; Layer couplings; Superlattices
Type
journal article