Infrared absorption study of charge ordered La(0.5)Ca(0.5-x)Sr(x)MnO(3) (0.1 less than or equal to x less than or equal to 0.5) manganites

Abstract

Infrared absorption study has been carried out on a series of half doped manganites, La(0.5)Ca(0.5-x)Sr(x)MnO(3) (0.1 less than or equal to x less than or equal to 0.5), with varying magnetic ground state. The charge ordering transition observed in samples with x less than or equal to 0.3 is accompanied by a mode at approx 525 cm(-1) in addition to the stretching mode at 615 cm(-1) and bending mode at 400 cm(-1). Phonon hardening is found to occur below the CE-type antiferromagnetic ordering temperature. The value of the insulating gap decreases on doping with Sr from 727 to 615 cm(-1).