Comparison of the in- and out-of-plane charge dynamics in YBa2Cu3O6.95 - art. no. 094501

The in-plane optical conductivity has been successfully employed to obtain information about the coupling of the charge carriers to the spin degrees o f freedom in the high-T-c oxides. We investigate how this inelastic scatter ing affects the out-of-plane charge dynamics. We consider both coherent (in -plane momentum is conserved) and incoherent (no momentum conservation) c-a xis transfers and find that the two cases give quite a distinct c-axis cond uctivity as a function of energy omega. Comparison of our theoretical calcu lations with the available data does not allow a definitive conclusion, but a momentum dependent coherent matrix element characteristic of the CuO2 ch emistry is favored with the possibility of a subdominant incoherent contrib ution.