  We report Electron Spin Resonance of the itinerant ferromagnets LaCrGe3,
CeCrGe3, and PrCrGe3. These compounds show well defined and very similar
spectra of itinerant Cr 3d spins in the paramagnetic temperature region. Upon
cooling and crossing the Cr-ferromagnetic ordering (below around 90 K) strong
spectral structures start to dominate the resonance spectra in a quite
different manner in the three compounds. In the Ce- and Pr-compounds the
resonance is only visible in the paramagnetic region whereas in the La-compound
the resonance can be followed far below the ferromagnetic ordering temperature.
This behavior will be discussed in terms of the specific interplay between the
4f and 3d magnetism which appears quite remarkable since CeCrGe3 displays heavy
fermion behavior even in the magnetically ordered state.
