Transport anomalies and marginal fermi-liquid effects at a quantum critical point

The behaviour of the conductivity and the density of states, as well as the phase relaxation time, of disordered itinerant electrons across a quantum ferromagnetic transition is discussed. It is shown that critical fluctuations lead to anomalies in the temperature and energy dependence of the conductivity and the tunnelling density of states, respectively, that are stronger than the usual weak-localisation anomalies in a disordered Fermi liquid. This can be used as an experimental probe of the quantum critical behaviour. The energy dependence of the phase relaxation time at criticality is shown to be that of a marginal Fermi liquid.