A reconstruction from small-angle neutron scattering measurements of the   real space magnetic field distribution in the mixed state of Sr$_2$RuO$_4$
  We have measured the diffracted neutron scattering intensities from the square magnetic flux lattice in the perovskite superconductor Sr$_2$RuO$_4$, which is thought to exhibit p-wave pairing with a two-component order parameter. The relative intensities of different Bragg reflections over a wide range of field and temperature have been shown to be inconsistent with a single component Ginzburg-Landau theory but qualitatively agree with a two component p-wave Ginzburg-Landau theory. 
P. G. Kealey, T. M. Riseman, E. M. Forgan, L. M. Galvin, A. P.   Mackenzie, S. L. Lee, D. McK. Paul, R. Cubitt, D. F. Agterb...