Field dependence of the resistive transition for a square wire network

We report the results of a study of square aluminum wire networks in a magnetic field. The ${\mathit{T}}_{\mathit{c}}$-versus-(Φ/${\mathrm{\Phi }}_0$) phase boundary defined at different points in the resistive transition was measured. When measuring low in the resistive transition, we see fine structure at rational fractions of the flux quantum f=Φ/${\mathrm{\Phi }}_0$=p/q, out to q=8. We also measured the field dependence of the resistive transition at many f=Φ/${\mathrm{\Phi }}_0$. The effect of the rational fields on the width of the transition is more dramatic than the effect on the phase boundary itself. Using a simple model, we can correctly order the width of the resistive transitions at the commensurate flux fillings.