Doping Dependent Density of States and Pseudogap Behavior in   La2-xSrxCuO4
  We have made a high-resolution photoemission study of La2-xSrxCuO4 in a wide hole concentration (x) range from a heavily overdoped metal to an undoped insulator. As x decreases, the spectral density of states at the chemical potential (\mu) is suppressed with an x-dependence similar to the suppression of the electronic specific heat coefficient. In the underdoped region, the spectra show a pseudogap structure on the energy scale of 0.1 eV. The width of the pseudogap increases with decreasing x following the x-dependence of the characteristic temperatures of the magnetic susceptibility and the Hall coefficient. 
A. Ino, T. Mizokawa, K. Kobayashi, A. Fujimori, T. Sasagawa, T.   Kimura, K. Kishio, K. Tamasaku, H. Eisaki and S. Uchida