Electrical characterization of a-axis oriented Y123 thin film grown using pulsed laser deposition

Abstract

The thin film of a-axis oriented YBa 2Cu 3O 7 (Y123) were grown on SrLaGaO 4 (100) substrate with a buffer layer of 50 nm thick Gd 2CuO 4 using pulsed laser deposition technique. The thickness of Y123 thin film is about 400 nm CuO 2 planes are aligned perpendicular to the substrate in the thin films. A micron-bridge was fabricated using focused ion beam milling technique in such a way that the current was forced to flow along the c-axis in thin film. Intrinsic Josephson junctions are aligned along the c-axis. The dimensions of bridge are 1 μm in length along the c-axis and 5 μm in width along the b-axis. Transition temperature ( T cON ) is about 84 K with single phase. The critical current density ( J c ) of 2 × 10 6 A/cm 2 was measured from current–voltage ( I–V) characteristics at 10 K. The samples were irradiated with external microwave of 20 GHz at different power and the J c was suppressed as we increased the power. This suppression in J c indicates the formation of layered structure with strong coupling. The voltage steps are appeared in non-linear I–V characteristics with microwave irradiation. The voltage steps are collective response of intrinsic Josephson junctions of micron-bridge.