YBaCuO superconducting films with Tc=90 K grown off-1:2:3 composition in low oxygen pressure

Abstract

YBaCuO films were grown in-situ by reactive coevaporation at low oxygen pressures. Films made at lower pressures (1-10 mTorr) and in non-equilibrium conditions have a c-axis lattice constant (cO) which is expanded compared to the films made at higher pressures (>100 mTorr). The authors have also found that at lower oxygen pressure off-1:2:3-composition and Ba-deficient films have higher Tc's (88-90 K) and lower cO than do films on-1:2:3 stoichiometry. They suggest that metal-atom point-like defects are quenched into the films at lower oxygen growth pressures.