The in-plane resistivity ${\mathrm{\rho }}_{\mathit{a}\mathit{b}}$(T) and Hall coefficient ${\mathit{R}}_{\mathit{H}}$(T) have been measured for ${\mathrm{YBa}}_2$${\mathrm{Cu}}_3$${\mathrm{O}}_{7\mathrm{-}\mathit{y}}$ single crystals with various oxygen concentrations. We find that for oxygen-depleted samples ${\mathrm{\rho }}_{\mathit{a}\mathit{b}}$(T) deviates from T-linear behavior and that ${\mathit{R}}_{\mathit{H}}$(T) deviates from 1/T below a temperature ${\mathit{T}}_{\mathit{o}}$ well above ${\mathit{T}}_{\mathit{c}}$. The deviation coincides with the development of a gap in the spin excitations seen in recent neutron and NMR studies. This is evidence that the charge transport in the ${\mathrm{CuO}}_2$ plane is determined by spin scattering.

• Received 17 December 1992

DOI:https://doi.org/10.1103/PhysRevLett.70.3995