Hall coefficient for oriented ${\mathrm{Tl}}_2$${\mathrm{Ba}}_2$${\mathrm{CaCu}}_2$${\mathrm{O}}_{8+\mathrm{\delta }}$ thin films

Measurements of the Hall coefficient and resistivity for highly oriented ${\mathrm{Tl}}_2$ ${\mathrm{Ba}}_2$ ${\mathrm{CaCu}}_2$ ${\mathrm{O}}_{8+\mathrm{\delta }}$ thin films are reported. The temperature dependence of cot${\mathrm{\Theta }}_{\mathit{H}}$, where ${\mathrm{\Theta }}_{\mathit{H}}$ is the normal-state Hall angle, for a single-phase (2:2:1:2) film sample and for other Tl-based phases is found to be linear in ${\mathit{T}}^2$. This behavior is in agreement with recent predictions based on Anderson’s spinon-holon model, but it is surprisingly general since it still holds for samples in which the resistivity does not follow Anderson’s predicted linear behavior and in which superconductivity is partially or completely suppressed.