Optical Response on the Colossal Magnetoresistance Effect in Manganites

The magnetorefractive effect in magnetoreflection and magnetotransmission modes in the optimally doped manganite epitaxial films possessed the colossal magnetoresistance effect was in the wide spectral region studied. The strict correlation between the magnetorefractive effect and colossal magnetoresistance in the middle infrared region for all samples was observed. It was shown that the magnetorefractive effect is an optical response to the colossal magnetoresistance in manganites. The magnetorefractive effect can reach a few tens of percents in the field of 3 kOe near the Curie point and can be explained by the change of ratio of localized and delocalized charge carriers under the magnetic field. On the contrary, in the visible range no direct correlations between magnetorefractive effect and colossal magnetoresistance were detected. The magnetorefractive effect is related with the alteration of the optical density under the magnetic field in the region of interband optical transitions. The magnitude of the effect is at least one order less in comparison with one in the infrared, but exceeds the values of traditional linear magnetooptical phenomena as the Kerr effect. Finally, huge magnetorefractive effect in manganites may be used for creation of various magnetic sensors and light modulation.