Low-energy excitations around (pi/2,pi/2) points in the pseudogap phase of Nd1.85Ce0.15CuO4

Polarized electronic Raman scattering from the Nd1.85Ce0.15CuO4, superconductor at optimal electron doping (T-c = 22 K) reveals the formation of an anisotropic pseudogap below a characteristic temperature T{*} approximate to 220 K and energy E-g{*} = 850 cm(-1). Below T{*} a pronounced suppression of the incoherent spectral weight below E-g{*} = 850 cm(-1) in the nodal directions of k space is observed. This is concomitant with the emergence of long-lived excitations in the vicinity of the (+/-pi/2,+/-pi/2) points that do not contribute to the optical conductivity.