  The magnetic moment induced by an external magnetic field of 5.8 T on the
Co3+ ions in LaCoO3 has been measured by polarized neutron diffraction.
Measurements were made at 100 K, near to the spin-state transition, at 1.5 K
and at 285 K. The data give evidence for a transition from the ground singlet
state (S = 0) to the excited triplet intermediate spin state (S = 1). The
energy of K estimated for the high-spin (S = 2) state, is too high to
contribute significantly even at T = 285 K. There is evidence for a small
negative covalent spin density associated with the oxygen ligands amounting to
about one fifth of the aligned Co3+ moment at all three temperatures.
