Photon-Induced Hopping in Bi2Sr2Ca0.5Y0.5Cu2Oy

Abstract
Transmission measurements of freestanding Bi2Sr2Ca0.5Y0.5Cu2O y crystals have been made in the frequency range from 10 to 12000 cm-1. Photon-induced hopping from occupied to unoccupied O-2p states was found in the absorption spectra from 10 to 5200 cm-1. The absorption edge at 11500 cm-1 due to charge transfer excitation and so-called mid-IR absorption from 1000 to 10000 cm-1 were also observed. Mid-IR absorption has been ascribed to a photon-induced hopping conduction edge continuing from the far-IR region.