Morphology and Electron Spin Resonance of the (La1−xSnx)2Mn2O7 Double Perovskite System

Shahid Husain ； Irshad Ahmad Bhat ； Wasi Khan ； Lila Alkhataby ； Ekrem Cicek

《Chinese Journal of Physics》 51卷3期 (2013/06) Pp. 551-559

https://doi.org/10.6122/CJP.51.551

並列摘要

We have synthesized (La1-xSnx)2Mn2O7 (x = 0.1, 0.15, and 0.25) samples using the solid state reaction (SSR) technique and the chemical reaction route (CRR). The powder X-ray diffraction (XRD) patterns show that all samples are in a single phase. The particle size distribution of the as prepared samples has been measured using scanning electron microscopy (SEM). Electron spin resonance (ESR) has proved to be useful for studying the spin dynamics of the Mn ion interaction mechanism and the dynamical Jahn-Teller distortions in perovskite manganites. We have recorded the ESR spectra at different temperatures in order to investigate the internal dynamical properties of the (La1.xSnx)2Mn2O7 system. We have observed that the intensity of the ESR line decreases exponentially with the temperature. The activation energy is calculated using the expression I(T) = I0 exp(Ea/kBT). In the high temperature region, 1/I(T) follows the Curie-Weiss law. The ESR line-width with respect to temperature, ΔH(T), for the samples was fitted to the one phonon process, ΔH(T) = A + BT, where A is constant and B is a parameter related to lattice distortions. The value of the parameter B decreases in both cases with an increase in Sn concentration, indicating a decrease in the lattice distortion.

參考文獻

J. Gao, S. Y. Dai, and T. K. Li, Phys. Rev. B 67, 153403 (2003).

A. Carrington and A. D. McLachlan, Introduction to Magnetic Resonance (Chapman and Hall, London-New York, 1980) p. 10.

A. Shengelaya, G. M. Zhao, H. Keller, and K. A. Muller, Phys. Rev. Lett. 77, 5296 (1996).

S. Dai, Z. W. Li, A. H. Morrish, X. Z. Zhou, J. G. Zhao and X. M. Xiong, et al., Phys. Rev. B 55, 14125 (1997).

Z. W. Li, A. H. Morrish, X. Z. Zhou, and S. Dai, J. Appl. Phys. 83, 7198 (1998).