  By using the extraordinary Hall effect in SrRuO3 films we performed sensitive
measurements of the paramagnetic susceptibility in this itinerant ferromagnet,
from Tc (~ 150 K) to 300 K. These measurements, combined with measurements of
magnetoresistance, reveal that the susceptibility, which is almost isotropic at
300 K, becomes highly anisotropic as the temperature is lowered, diverging
along a single crystallographic direction in the vicinity of Tc. The results
provide a striking manifestation of the effect of exceptionally large
magnetocrystalline anisotropy in the paramagnetic state of a 4d itinerant
ferromagnet.
