Local epitaxy of Ag on Bi₂Sr₂CaCu₂O_8+x(001)

Thin films of Ag have been deposited onto cleaved Bi₂Sr₂CaCu₂O_8+x(001) surfaces at room temperature. Ag 3<i>d</i> x-ray photoelectron diffraction experiments show very poor local order at coverages of up to 7 Å. For higher Ag coverages, a distinct diffraction pattern is forming, indicative of local epitaxy in the form of two domains of Ag(110) patches with one diagonal of the rectangular surface unit cell aligned along the substrate a axis. Comparison with previously published scanning-tunneling-microscopy results [Y. S. Luo <i>vet al. </i>, Phys. Rev. B <b>46</b>, 1114 (1992)] leads us to the conclusion that Ag epitaxy is promoted by local disruption of the substrate upon initial Ag deposition.