Abstract

The topic of this talk is the non-Fermi-liquid region that appears in two-dimensional metals in the vicinity of a ferromagnetic quantum critical point. After a brief introduction to the (long) history of this problem, I will summarise the results of our recent calculation, which is performed using the functional renormalisation group (fRG) technique. The new feature that this allows us to explore is whether the damping rate of a magnetic fluctuation can depend on the wavevector differently than it does in a perturbative calculation. We shall find that it can; indeed, our fRG analysis yields a fixed point at which the fermions are non-Fermi-liquid (with a dynamical exponent z_f = 7/6) and the magnetic fluctuations have a damping rate that goes like the cube root of their wavevector rather than the usual linear behaviour. I will discuss the implications of this finding, as well as potential avenues for future work on the problem.