Temperature dependence of the relaxation of photoexcited (PE) carriers is used as a probe of the electronic structure of the high-temperature superconductor YBa₂Cu₃O_{7- (delta} ) ((delta) approximately equals 0.1). The relaxation process is studied by 'counting' -- through measurement of the Raman scattering Stokes/anti-Stokes intensity ratio -- the phonons emitted in the process of carrier energy relaxation. The phonon 'shake-off' is found to be strongly temperature dependent, implying that the PE carrier relaxation proceeds via a temperature activated process, which can be understood in terms of hopping between localized states. The long PE carrier lifetime and temperature dependence of the relaxation process implies the existence of localized states within 2 eV of the Fermi energy in optimally doped high-T_c superconductor.

Date Published: 10 June 1996
PDF: 6 pages
Proc. SPIE 2696, Spectroscopic Studies of Superconductors, (10 June 1996); doi: 10.1117/12.241774

Published in SPIE Proceedings Vol. 2696:
Spectroscopic Studies of Superconductors
Ivan Bozovic; Dirk van der Marel, Editor(s)