Transient Photoinduced Conductivity in Semiconducting Single Crystals of YBa2Cu3O6.3: Search for Photoinduced Metallic State and for Photoinduced Superconductivity.

摘要

We present the results of time resolved experiments on single crystals of YBa2Cu3O6.3 mounted in the Auston switch configuration. At 300K, the peak photocurrent is linear in the pump light intensity at low light levels and saturates at the highest light levels available. Below 200K, the peak photocurrent increases approximately linearly with the pump light intensity at low light levels, but shows an increase to superlinear behavior above approx 5 x 10 to the 15th power photons/sq. cm, indicative of the onset of an additional transport mechanism. At 50K, the transient decrease in the resistance indicates a photoinduced change in resistivity within the absorption depth of the light by more than 14 orders of magnitude. The photoinduced conductivity is time delayed with respect to the absorption; approximately 0.5 ns is required for the photoexcited system to evolve to a highly conducting state. The results are discussed in terms of the possibility of a photoinduced transition to the metallic state and of photoinduced superconductivity. Reprints. (AW)