Evolution of the quasiparticle spectral function in cuprates
  We analyzed photoemssion data for several doping levels of the Bi_2Sr_2CaCu_2O_{8+x} compounds, ranging from overdoped to underdoped. We show that the high frequency part of the spectra near (0,\pi) can be described by Fermi liquid theory in the overdoped regime, but exhibits a non-Fermi liquid behavior in the underdoped regime. We further demonstrate that this novel behavior fits reasonably well to a 1/\sqrt{\omega} behavior suggested for systems with strong spin fluctuations. 
S. Misra(1), R. Gatt(1), T. Schmauder(1), Andrey V. Chubukov(1), M.   Onellion(1), M. Zacchigna(2), I. Vobornik(2), F. Zwick...