title: An ultrasonic study on complex charge ordering phenomena for La(1-x)Sr(x)FeO(3).
abstract: The complex charge ordering phenomena for polycrystalline La(1-x)Sr(x)FeO(3) (1/3≤x≤2/3) have been studied by measuring the low temperature magnetization, resistivity and the longitudinal ultrasonic velocity (V(l)). At low doping levels (1/3≤x≤0.5), a dramatic velocity increase is observed below 210 K, and the relative stiffening of V(l) is proportional to the Sr concentration. The analysis suggests that this feature may correspond to the short-range charge ordering state of Fe(3+) and Fe(4+). At high doping levels (0.5<x≤2/3), the resistivity shows a sharp increase around 200 K, and the relative stiffening of V(l) decreases with increasing x. This implies that the charge disproportionation transition [Formula: see text] occurs. In particular, the V(l) of La(1/3)Sr(2/3)FeO(3) undergoes another softening transition below 181 K, which is attributed to the breathing-type distortion of Fe-O octahedron in the sequence...Fe(3+)Fe(5+)Fe(3+).... The detailed form of the sound velocity anomalies in La(1-x)Sr(x)FeO(3) (x = 1/3,2/3) is different, revealing the presence of complex charge ordering phenomena. To complete the ultrasonic characterization in La(1-x)Sr(x)FeO(3), sound measurements were performed on La(0.1)Sr(0.9)FeO(3), whose ground state is a typical antiferromagnetic order, and the anomaly is small.
authors.affiliation: Laboratory of Advanced Functional Materials and Devices, Department of Materials Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China.
authors.forename: Hui
authors.initials: H
authors.lastname: Kong
authors.forename: Changfei
authors.initials: C
authors.lastname: Zhu