  Magnetic diffusion in accretion flows changes the structure and angular
momentum of the accreting material. We present two power law similarity
solutions for flattened accretion flows in the presence of magnetic diffusion:
a secularly-evolving Keplerian disc and a magnetically-diluted free fall onto
the central object. The influence of Hall diffusion on the solutions is evident
even when this is small compared to ambipolar and Ohmic diffusion, as the
surface density, accretion rate and angular momentum in the flow all depend
upon the product \eta_H(B.\Omega), and the inclusion of Hall diffusion may be
the solution to the magnetic braking catastrophe of star formation simulations.
