  We found that the length of the Fermi arc decreases with increasing
out-of-plane disorder by performing angle resolved photoemission spectroscopy
(ARPES) measurements in the superconducting state of optimally doped R=La and
Eu samples of Bi2Sr2&#8722;xRxCuOy. Since out-of-plane disorder stabilizes the
antinodal pseudogap as was shown in our previous study of the normal state, the
present results indicate that this antinodal pseudogap persists into the
superconducting state and decreases the Fermi arc length. We think that the
shrinkage of the Fermi arc reduces the superfluid density, which explains the
large suppression of the superconducting transition temperature when
out-of-plane disorder is increased.
