Quantum Correction to Conductivity Close to a Ferromagnetic Quantum Critical Point in Two Dimensions

We study the temperature dependence of the conductivity due to quantum interference processes for a two-dimensional disordered itinerant electron system close to a ferromagnetic quantum critical point. Near the quantum critical point, the crossover between diffusive and ballistic regimes of quantum interference effects occurs at a temperature T^*=1/τγ(E_Fτ)², where γ is the parameter associated with the Landau damping of the spin fluctuations, τ is the impurity scattering time, and E_F is the Fermi energy. For a generic choice of parameters, T^* is smaller than the nominal crossover scale 1/τ. In the ballistic quantum critical regime, the conductivity behaves as T^1/3.