Large infrared magnetotransmission effect in composite and nano-composite based on Nd_(0.5)Sr_(0.5)MnO_3

摘要

Large negative magnetotransmission effect △t/t_O = (t_H - t_O)Ao (where t_H, t_O are the light transmissions with and without magnetic field, respectively) of up to 9% was revealed in composites contained coarse-grained and nano-powders of Nd_(0.5)Sr_(0.5)MnO_3 in the infrared (IR) range near the Curie temperature in magnetic field H = 8 kOe. The optical density spectra and magnetotransmission effect of the composites are discussed in the context of the polar centers phase model. In the nano-powder composite, the significant magnetotransmission of ～7% takes place in wide temperature region far below T_C. This fact is explained by the existence of the localized charge carriers and spin disorder at the nano-particles surface. An applied magnetic field reduces spin disorder and the localization of charge carriers resulting in negative magnetotransmission effect. Two magnetic phase transitions and phase separation in Nd_(0.5)Sr_(0.5)MnO_3 promote the large magnetotransmission effect in a wide temperature range. The Nd_(0.5)Sr_(0.5)MnO_3 nano-powder composite is a promising material for magnetooptical devices with a wide working temperature range.