NEW METHOD OF NON-FERMI LIQUID STUDY BY PUMP-SUPERCONTINUUM PROBE FEMTOSECOND SPECTROSCOPY

A new method of investigation of Fermi surface and Fermi liquid (FL) v ersus non-Fermi liquid (NFL) behavior in strongly correlated electron systems by femtosecond laser spectroscopy is proposed. The method cons ists in study of spectral dependence of the nonequilibrium charge carr iers relaxation time by pump-supercontinuum probe technique. This meth od is demonstrated on high-T-c oxide superconductor YBa2Cu3O7-delta by studying the temporary changes of optical density of YBa2Cu3O7-delta thin film in a wide spectral region of probing, (h) over bar omega(pro be) = 1.6-3.0 eV. The relaxation time sharply grows in the spectral ar ea, related to optical transitions into the vicinity of the Fermi leve l (or its shadow). The position of this peak gives the location of the Fermi surface (FS). The form of the peak gives unique information on the damping rate near the FS and, thus, on the FL vs. NFL behavior.