Quantum Critical Point in Electron-Doped Cuprates

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We analyze doping dependent spectral intensities and Fermi surface maps obtained recently in Nd₂₋ₓCeₓCuO₄±δ (NCCO) via high resolution ARPES measurements, and show that the behavior of this electron-doped compound can be understood as the closing of a Mott (pseudo) gap, leading to a quantum critical point just above optimal doping. The doping dependence of the effective Hubbard U adduced by comparing theoretical and experimental spectra is in resonable accord with various estimates and a simple screening calculation.