Disorder-induced polaron formation in the magnetoresistive perovskite La0.54Ba0.46MnO3.
Neutron studies of the effect of A-site chemical disorder on the ferromagnetic transition and spin dynamics for the magnetoresistive perovskite La0.54Ba0.46MnO3 are reported. The low temperature spin waves reveal that disorder reduces exchange interactions by only 9%. The development of a quasielastic peak in the spectrum below TC and long-time relaxation of the order parameter indicate that the transition is discontinuous in the disordered sample, while it appears continuous for the ordered sample. These results strongly suggest that chemical disorder lowers the energy for polaron formation in manganese perovskites, and is the origin of the dramatic 50 K reduction in TC.
Sato
T J
TJ
NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8562, USA. taku@issp.u-toyko.ac.jp
Lynn
J W
JW
Dabrowski
B
B