Quantum ferromagnetic transition in disordered itinerant electron systems

An effective field theory is derived for the ferromagnetic transition of diffusive electrons at T = 0. The static disorder which leads to diffusive electron dynamics induces an effective long-range interaction between the spins of the form 1/r(2d-2). This leads to unusual scaling behavior at the quantum critical point, which is determined exactly. The crossover from this quantum fixed point to the classical Heisenberg fixed point should be observable in ferromagnetic materials with low Curie temperatures.