Interplay of Disorder and Spin Fluctuations in the Resistivity near a Quantum Critical Point

The resistivity in metals near an antiferromagnetic quantum critical point (QCP) is strongly affected by small amounts of disorder. In a quasiclassical treatment, we show that an interplay of strongly anisotropic scattering due to spin fluctuations and isotropic impurity scattering leads to a large regime where the resistivity varies as T^α, with an anomalous exponent, 1α1.5, depending on the amount of disorder. I argue that this mechanism explains in some detail the anomalous temperature dependence of the resistivity observed in CePd₂Si₂, CeNi₂Ge₂, and CeIn₃ near the QCP.