Important modifications near a magnetic instability in the particle-hole propagator of weakly localized two-dimensional fermion systems

Abstract

In the Hubbard-type paramagnon model important changes arise in the particle-hole propagator structure for weakly disordered, two-dimensional (2d), strongly interacting itinerant-fermion systems near a magnetic instability, when all momenta up to twice the Fermi momentum (0\ensuremath{\le}q\ensuremath{\le}2${k}_{F}$) are equally relevant. In 3d systems, the only vanishing momentum values (q\ensuremath{\sim}0) are the key ones, for which only the diffusive regime arises in the case of weak localization; in contrast, in 2d nearly magnetic systems, other regimes, in addition to the diffusive one, must be taken into account and be considered as playing equally important roles. Different temperature dependences follow for the physical properties of the system which furthermore do not vary the same way with the impurity concentration. Their relative weights are affected accordingly, which will be of importance for comparison with experiments.