The nature of the polarons in the optimally doped colossal magnetoresistive (CMR) materials La0.7Ba0.3 (LBMO and La0.7Sr0.3MnO3 (LSMO is studied by elastic and inelastic neutron scattering. In both materials, dynamic nanoscale polaron correlations develop abruptly in the ferromagnetic state. However, the polarons are not able to lock-in to the lattice and order, in contrast to the behavior of La0.7Ca0.3MnO3 (LCMO). Therefore ferromagnetic order in LBMO and LSMO survives their formation, explaining the conventional second order nature of the ferromagnetic-paramagnetic transition. Nevertheless, the results deomonstrate that the fundamental mechanism of of polaron formation is a universal feature of these ferromagnetic perovskite manganites.
Citation: Physical Review Letters
Pub Type: Journals
Phonons, Colossal Magnetoresistance, Polarons, Inelastic Neutron Scattering, Manganites, Ferromagnet