Complete Fermi surface mapping of Bi₂Sr₂CaCu₂O_8+x(001): Coexistence of short range antiferromagnetic correlations and metallicity in the same phase

The Fermi surface of Bi₂Sr₂CaCu₂O_8+x(001) has been mapped at nearly 6000 points in <b>k</b> space using angle-resolved photoemission at 300 K. We observe both features that are in good agreement with the local density calculation of Massidda, Yu, and Freeman [Physica (Amsterdam) <b>158C</b>, 251 (1988)] and others that are missing in the calculation. Among those missing, most importantly, we find a <i>c</i> (2×2) superstructure on the Fermi surface strongly suggesting short range antiferromagnetic correlations. It is remarkable that this is evident in the metallic state and in the Fermi surface itself.