Colossal magnetoresistance materials are archetypes in which
to study the effects of strong coupling between the spin,
charge and lattice degrees of freedom in materials.
These effects include formation of spin-lattice polarons,
charge and orbital ordering, extreme sensitivity to
applied magnetic fields and inhomogeneous spin dynamics.
The muon spin relaxation (SR) technique provides a
powerful local magnetic probe with which to investigate
the spin degrees of freedom in these materials.
A survey of the zero-field magnetic properties
of the series La1-xCaxMnO3 using SR will
presented, with particular emphasis on the
ferromagnetic ground state materials.
It is found that there are several
characteristic relaxation modes which
are produced as a direct result of the
strong spin-charge-lattice interaction.
Results from inelastic neutron spin echo
scattering, which directly measures the spin-spin
correlation function, will also be presented and
compared to the SR data. A qualitative model
for the ferromagnetic transition in the
manganites suggested by these data will be discussed.