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L. Hozoi, M. S. Laad, and P. Fulde Max Planck Institute for the Physics of Complex Systems, Dresden We report results of fully ab-initio, wavefunction-based quantum chemical calculations describing correlated electron-removal and electron-addition quasiparticle states in layered copper oxides. In particular, the computed quasiparticle dispersion and Fermi-surface (FS) evolution with doping are compared with recent ARPES (angle-resolved photoemission spectroscopy) and SdH (Shubnikov-deHaas) measurements. We find that the FS evolves as a function of hole doping from small hole pockets in the deeply underdoped regime, via one with both hole- and electron-like sheets at slightly higher hole doping, to a large FS consistent with Luttinger's theorem at still higher doping levels. Beyond a critical hole concentration, it also becomes electron-like, in agreement with ARPES measurements. These findings permit us to offer a resolution of the controversy generated by the apparent inconsistency between the SdH data and the Luttinger sum rule for underdoped cuprates, as well as with the recent Hall-effect measurements suggesting an electron-like Hall constant for hole doped cuprates at low temperatures. Specifically, the presence of both hole- and electron-like sheets in the underdoped regime permits one to understand why the SdH results showing a density of charge carriers of 0.15 are reconcilable with Luttinger's theorem, which would imply a hole density of 0.10 at 10 percent doping. The electron-like Hall constant at low-T can now be rationalized in terms of having both hole- and electron-like quasiparticles with different densities and mobilities. Our approach addresses these issues from a first principles perspective, in contrast to alternative schemes, where a partial subset of these issues remains to be addressed, in spite of tremendous progress. |
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