  Mesoscopic (500-2000 Angstrom) and microscopic (5-20 Angstrom) phase
segregation with temperature and magnetic field was studied in the model
manganite Pr0.7Ca0.3MnO3 by high-resolution neutron diffraction and inelastic
neutron scattering. Intra-granular strain-driven mesoscopic segregation between
two insulating phases, one of which is charge ordered (CO), sets in below the
CO temperature in zero field. The CO phase orders antiferromagnetically, while
the other insulating phase shows spin-glass behavior. After field-induced
metallization, the CO phase coexists with a ferromagnetic metallic phase.
