Hall effect of Bi-Sr-Ca-Cu-O and Tl-Ba-Ca-Cu-O systems

The Hall coefficient $R_H$ has been measured in Bi-Sr-Ca-Cu-O and Tl-Ba-Ca-Cu-O systems as a function of temperature. In all the systems $R_H^{\mathrm{-}1}$ varies linearly with temperature. $T_c$ decreases as the filling factor ν ($n_H$ normalized to Cu ions present in the unit cell) increases in the Bi and Tl systems. This behavior is opposite in nature to that observed in the ${\mathrm{La}}_{2\mathrm{-}\mathrm{x}}$ ${\mathrm{Sr}}_{\mathrm{x}}$ ${\mathrm{CuO}}_4$ and ${\mathrm{YBa}}_2$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_{7\mathrm{-}\mathrm{x}}$ systems.