Observation of an unconventional metal-insulator transition in overdoped CuO2 compounds -: art. no. 107003

The electron dynamics in the normal state of Bi2Sr2CaCu2O8+delta is studied by inelastic light scattering over a wide range of doping. A strong anisotropy of the electron relaxation is found which cannot be explained by single-particle properties alone. The results strongly indicate the presence of an unconventional quantum-critical metal-insulator transition where hot (antinodal) quasiparticles become insulating while cold (nodal) quasiparticles remain metallic. A phenomenology is developed which allows a quantitative understanding of the Raman results and provides a scenario which links single- and many-particle properties.