  55Mn and 139La NMR measurements on a high quality single crystal of
ferromagnetic (FM) La0.80Ca20MnO3 demonstrate the formation of localized
Mn(3+,4+) states below 70 K, accompanied with strong anomalous increase of
certain FM neutron Bragg peaks. (55,139)(1/T1) spin-lattice relaxation rates
diverge on approaching this temperature from below, signalling a genuine phase
transition at T(tr) approx. 70 K. The increased local magnetic anisotropy of
the low temperature phase, the cooling-rate dependence of the Bragg peaks, and
the observed finite size scaling of T(tr) with Ca (hole) doping, are suggestive
of freezing into an orbital domain state, precursor to a phase transition into
an inhomogeneous orbitally ordered state embodying hole-rich walls.
