Anomalous spectral weight transfer at the superconducting transition ofBi2Sr2CaCu2O8+δ

Abstract

Anomalous spectral weight transfer at the superconducting transition of single-crystalline ${\mathrm{Bi}}_{2}$${\mathrm{Sr}}_{2}$${\mathrm{CaCu}}_{2}$${\mathrm{O}}_{8+\mathrm{\ensuremath{\delta}}}$ was observed by high-resolution angle-resolved photoemission spectroscopy. As the sample goes superconducting, not only is there spectral weight transfer from the gap region to the pileup peak as in BCS theory, but along the \ensuremath{\Gamma}-M\ifmmode\bar\else\textasciimacron\fi{} direction there is also some spectral weight transfer from higher binding energies in the form of a dip. In addition, we note that at the superconducting transition there is a decrease (increase) in the occupied spectral weight for the spectra taken along \ensuremath{\Gamma}-M\ifmmode\bar\else\textasciimacron\fi{} (\ensuremath{\Gamma}-X).