Resistivity and T c measurements on YBa2(Cu1−xMx)3O7−δ films (M=Ni,Al)

Abstract
YBa2(Cu1−xMx)3O7−δ films (M=Ni and Al) with up to 11 at. % dopant are fabricated on (001) SrTiO3 substrates by codeposition of Y, BaF2, Cu, and M, and then post‐annealing in moist oxygen. All films are 300 nm thick. They are highly oriented with the c axis perpendicular to the substrate, and their surfaces are as smooth as for undoped YBa2Cu3O7−δ films. Tc(x) decreases with x consistent with bulk ceramic samples. The resistivity is metallic and ranges from 100 μΩ cm to 2.5 mΩ cm at 100 K. The residual resistivity ρab(0) at T=0 K, extrapolated from ρab(T) above Tc is approximately proportional to x up to 7 at. % Al films and 11 at. % Ni.