Magnetotransport studies of optimally doped Sr(Fe_1-x Co _x )₂As₂

We report magnetotransport measurements and their scaling analysis for the optimally electron-doped Sr(Fe_0.88Co[Formula: see text]As₂ system. We observe that both the Kohler's and modified Kohler's scalings are violated. Interestingly, the Hall angle displays a quadratic temperature dependence (cot[Formula: see text] [Formula: see text] T ²) similar to many cuprates and heavy fermion systems. The fact that this T ² dependence is seen in spite of the violation of modified Kohler's scaling suggests that the Hall angle and magnetoresistance are not governed by the same scattering mechanism. We also observe a linear magnetoresistance in this system, which does not harbor a spin density wave ground state. Implications of our observations are discussed in the context of existing models for the magnetotransport of these strongly correlated electron systems.