Abstract
Thin films of the electron-doped superconductor Nd1.85Ce0.15CuO4-y (NCCO) have been fabricated on (100) SrTiO3 substrates by inverted cylinder magnetron sputtering. By optimizing the reduction step subsequent to the deposition, superconducting thin films with a transition temperature Tc(R = 0) = 22.5 K and zero-field critical current density Jc {reversed tilde equals} 1.7 × 106 A/cm2 at T = 4.2 K could be obtained. Also, epitaxial YBCO/NCCO bilayers in which both materials are superconducting could be fabricated. The mixed state of the NCCO films has been characterized by measuring the longitudinal resistivity as well as the Nernst and Seebeck effects in magnetic fields up to 6 T applied parallel to the c-axis. From these measurements an upper critical field slope dBc2/dT = -0.35 T/K was obtained for films with Tc {reversed tilde equals} 22 K corresponding to an ab-plane coherence length ξab = 80 A ̊. The transport energy of magnetic flux lines was derived to dUφ/dT = -2.4 × 10-13 J/Km. The transport entropy of magnetic flux lines was obtained to Sφ = 1.6 × 10-14 J/K m at T = 18 K and B = 0.5 T in good agreement with the prediction of time-dependent Ginzburg-Landau theory.
Original language | English |
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Pages (from-to) | 389-399 |
Number of pages | 11 |
Journal | Physica C: Superconductivity and its Applications |
Volume | 244 |
Issue number | 3-4 |
DOIs | |
State | Published - 20 Mar 1995 |
Externally published | Yes |