Effect of Zn impurities on the normal-state Hall angle in single-crystal ${\mathrm{YBa}}_2$${\mathrm{Cu}}_{3\mathrm{-}\mathit{x}}$${\mathrm{Zn}}_{\mathit{x}}$${\mathrm{O}}_{7\mathrm{-}\mathrm{\delta }}$

In Zn-doped single-crystal ${\mathrm{YBa}}_2$${\mathrm{Cu}}_{3\mathrm{-}\mathit{x}}$${\mathrm{Zn}}_{\mathit{x}}$${\mathrm{O}}_{7\mathrm{-}\mathrm{\delta }}$ we show that the normal-state Hall angle varies as cot${\mathrm{\theta }}_{\mathit{H}}$=α${\mathit{T}}^2$+βx, as predicted by Anderson (T is temperature). The existence of two distinct relaxation time scales (${\mathrm{\tau }}_{\mathit{H}}$∼1/${\mathit{T}}^2$ and ${\mathrm{\tau }}_{\mathrm{tr}}$∼1/T), required by experiment, precludes all multi-band Drude-type models. A number of puzzling features of the Hall effect in the cuprates are resolved with the new analysis. We also report an improved measurement of the scattering cross section of Zn in the ${\mathrm{CuO}}_2$ planes.