In-situ growth of superconducting YBa 2Cu 3O 7 - δ thin films at low oxygen partial pressures

Abstract

In-situ superconducting c-axis oriented YBa 2Cu 3O 7 - δ (YBCO) thin films have been grown at T sub = 775 °C on SrTiO 3(100) and MgO(100) by r.f.-magnetron sputtering at an oxygen partial pressure, which not only lies below the stability line but is more than an order of magnitude lower than its empirically suggested limit. The effect of variation in partial pressure of oxygen ( P o 2 ) on the film characteristics is analyzed by employing a.c.-magnetic susceptibility, resistance-temperature variation, Rutherford backscattering, atomic force microscopy (AFM), scanning electron microscopy and X-ray diffraction techniques. The oxygen deficiency, δ, is calculated employing a number of techniques. The higher c-axis lattice parameters of the films are supportive of antisite disorder in the cations. The AFM investigations have established that Stranski-Krastanov-type growth mechanism is operative in the present case. The variation in critical current density ( J mag c( T)) with temperature is reported for the first time in the low pressure sputtered films exhibiting a J mag c(43 K) of ≈4.6 × 10 6 A cm -2.