Disorder effects on transport near AFMquantum phase transitions

We discuss three different scenarios recently proposed to account for the non-Fermi liquid behavior near antiferromagnetic (AFM) quantum critical points in heavy-Fermion systems: (i) scattering of Fermi liquid quasiparticles by strong spin fluctuations near the spin-density-wave instability, (ii) the breakdown of the Kondo effect due to the competition with the RKKY interaction, and (iii) the formation of magnetic regions due to rare configurations of the disorder. Here we focus on the first scenario and show that it explains in some detail the anomalous temperature dependence of the resistivity observed e.g. in CePd2Si2, CeNi2Ge2 or CeIn3. The interplay of strongly anisotropic scattering due to critical spin-fluctuations and weak isotropic impurity scattering leads to a regime with a resistivity ρ ≈ ρ0 +∆ρ(T ), ∆ρ(T ) ≡ T f(T/ρ0) ∝ T √ ρ0 for sufficiently large T and small ρ0.