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Ultrasonic anomaly near the charge ordering transition in Sr-doped Nd0.3La0.2Ca0.5−xSrxMnO3 manganites

Shamsuddin, S. and Supardan, S. N. and M. A. Ibrahim, Abdel-Baset and Yahya, A. K. (2013) Ultrasonic anomaly near the charge ordering transition in Sr-doped Nd0.3La0.2Ca0.5−xSrxMnO3 manganites. Journal of Superconductivity and Novel Magnetism, 27. pp. 1229-1234. ISSN 15571939

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Sr doping in the charge-ordered compound Nd0.3La0.2Ca0.5−xSrxMnO3 has been systematically studied to examine its effect on ultrasonic velocity and elastic moduli as well as magnetic and electrical transport properties. DC electrical resistivity, ρ and AC susceptibility, χ1 measurements showed all samples exhibit metal-insulator (MI) behavior accompanied by ferromagnetic-paramagnetic (FM-PM) transition where the MI transition temperature, TMI and FM-PM transition temperature, TC increased with Sr content indicating the enhancement of double-exchange mechanism. Analysis of the resistivity change with respect to temperature, d lnρ/dT −1 versus T indicates onset of charge-ordering (CO) state where its CO transition temperature, TCO decreased with Sr content indicating weakening of the CO state. On the other hand, both absolute longitudinal and shear velocities as well as elastic moduli measured at 80 K increased significantly with Sr doping indicating improvement in elastic properties, which is suggested to be due to the increase in formation of ferromagnetic domains. A longitudinal velocity anomaly characterized by a slope change around the vicinity of TCO was observed for all samples. The longitudinal elastic anomaly is attributed to the Jahn–Teller (JT) effect of Mn3+ ions where analysis of the anomaly using the mean-field theory suggests involvement of the JT effect in the samples, which transforms from dynamic to static type with decreasing temperature. The elastic anomaly shifted down from 222 K (x = 0) to 205 K (x = 0.05) indicating that the static JT effect was weakened with Sr content.

Item Type: Article
Uncontrolled Keywords: Charge ordering; double-exchange mechanism; Jahn–Teller effect; ultrasonic anomaly
Subjects: Q Science > QC Physics
Depositing User: Mr. Mohammad Shaifulrip Ithnin
Date Deposited: 13 Aug 2018 03:21
Last Modified: 13 Aug 2018 03:21
URI: http://eprints.uthm.edu.my/id/eprint/9823
Statistic Details: View Download Statistic

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