Complex charge ordering phenomena in La1-xSrxFeO3-δ investigated by mechanical spectroscopy

The presence of complex charge ordering phenomena in La1-xSrxFeO3-delta (x = 0.55, 0.60, 0.67, and 0.72) has been studied by kilohertz mechanical spectroscopy. With the decrease in temperature, a step increase of the modulus and decrease of internal friction were observed around the charge ordering transition temperature in La1-xSrxFeO3-delta. This characteristic behavior preserves in La1-xSrxFeO3-delta (x = 0.55, 0.60, and 0.72), which suggests the existence of charge ordering. An internal friction peak around 160K in La1-xSrxFeO3-delta (x = 0.55 and 0.60) is identified as an elastic manifestation of magnetic freezing. The description of the electronic phase diagram is obtained and it supports an ionic picture. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4767354]