Interplay of structural and electronic phase separation in single-crystalline La 2 CuO 4.05 studied by neutron and Raman scattering

We report a neutron- and Raman-scattering study of a single crystal of La2CuO4.05 prepared by hightemperature electrochemical oxidation. Elastic neutron-scattering measurements show the presence of two phases, corresponding to the two edges of the first miscibility gap, all the way up to 300 K. An additional oxygen redistribution, driven by electronic energies, is identified at 250 K in Raman scattering ~RS! experiments by the simultaneous onset of two-phonon and two-magnon scattering, which are fingerprints of the insulating phase. Elastic neutron-scattering measurements show directly an antiferromagnetic ordering below a