Superconductivity suppression in YBa2Cu3O7-δ/La0.7Sr0.3MnO3 bilayer films

Abstract

We study the thickness effect of YBa2Cu3O7−δ (YBCO) in YBCO/La0.7Sr0.3MnO3 (LSMO) bilayer films, fabricated on LaAlO3 (001) substrate using pulsed laser deposition technique. The thickness dependent transport behavior of YBCO layer in considered bilayer systems demonstrate a clear onset critical temperature at 60 K and 80 K for 100 nm and 200 nm thick YBCO layer systems, respectively, whereas 50 nm thick YBCO system reveals complete suppression in the superconductivity. With the increase in thickness of YBCO layer, the magnetoresistance (MR) data show both positive and negative MR. The positive MR in superconducting regime dominates the negative MR, suppress the double exchange interaction. The maximum magnetoresistance ratio ∼81% at 64 K and ∼47% at 30 K temperature are observed for 200 nm and 100 nm YBCO layers, respectively. In YBCO(200 nm)/LSMO(200 nm) bilayer specimen, the temperature co-efficient of resistance is ∼8.4% K−1 at 72 K which can be practical for bolometric performances and temperature sensors.