Shadow bands in overdoped Bi_2Sr_2CaCu_2O_{8+x}

Abstract

We performed angle-resolved photoemission experiments on overdoped single crystal $Bi_2Sr_2CaCu_2O_{8+x}$ samples with Tc values as low as 55K and very narrow transitions as measured by AC susceptibility. The photoemission data indicate the presence of a ``shadow'' peak in the quasiparticle spectral function $A(ω)$ shifted by $(π,π)$ from the conventional quasiparticle peak. The ratio of the shadow/quasiparticle peak amplitudes strongly increases with the binding energy. This is consistent with the idea that the shadow peak is not a structural replica of the quasiparticle peak, but rather a maximum in a spectral function which can exist due to interaction with spin fluctuations peaked at $(π,π)$.