Lattice effect on charge and magnetic ordering in La _1/3 Sr _2/3 FeO _{3− δ} investigated by mechanical spectroscopy

Abstract

We present an investigation on high-temperature tilting transition and low-temperature charge and magnetic ordering in La1/3 Sr2/3 FeO3−δ by mechanical spectroscopy. An octahedral tilting transition appears around 500 K showing up as a huge modulus softening with the decrease in temperature in nearly oxygen stoichiometric La1/3 Sr2/3 FeO3−δ. The modulus softening is mainly due to ferroelastic domain wall motion in rhombohedral structure. A modulus hardening appears at the charge and magnetic ordering. It is expected that the charge and magnetic ordering partially pins the ferroelastic domain walls in La1/3 Sr2/3 FeO3−δ. This proposal was further investigated in a slight oxygen nonstoichiometric La1/3 Sr2/3 FeO3−δ sample and different high-temperature annealed La1/3 Sr2/3 FeO3−δ samples. Our work suggests a special magnetoelastic coupling, the pinning of ferroelastic domain walls by magnetic interaction in La1/3 Sr2/3 FeO3−δ.