Magnetic Anisotropy in La_0.8Sr_0.2MnO_3: Electron Spin Resonance
  We report on Ferromagnetic-Resonance experiments in a single crystal of La_0.8Sr_0.2MnO_3 in the temperature range from 4 to 300 K. The observed anisotropy of the resonance line changes on crossing the transition from the orthorhombic O-phase to the rhombohedral R-phase at T~100 K and indicates a reorientation of the spins at about 130 K. 
J. Deisenhofer, H.-A. Krug von Nidda, A. Loidl, M.V. Eremin, V.A.   Ivanshin, T. Kimura and Y. Tokura