We have grown epitaxial films of the ${\mathrm{YBa}}_2$${\mathrm{Cu}}_3$${\mathrm{O}}_{7\mathrm{-}\mathrm{x}}$ compound on ${\mathrm{SrTiO}}_3$ substrates. The superconducting critical current in these films at 77 K is in excess of ${10}^5$ A/${\mathrm{cm}}^2$ and at 4.2 K in excess of ${10}^6$ A/${\mathrm{cm}}^2$.

• Received 11 May 1987

DOI:https://doi.org/10.1103/PhysRevLett.58.2684