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• 研究论文 • 上一篇    下一篇

La2/3(Ca,Ba)1/3MnO3系统的顺磁共振研究

彭刚1; 袁松柳1; 金嗣昭2   

  1. 1. 华中科技大学物理系; 武汉 420074; 2. 中国科技大学结构分析中心 合肥 230026
  • 收稿日期:2001-11-21 修回日期:2002-04-19 出版日期:2003-01-20 网络出版日期:2003-01-20

Electron Paramagnetic Resonance Measurements of La2/3 (Ca,Ba)1/3MnO3

PENG Gang1; YUAN Song-Liu1; JIN Si-Zhao2   

  1. 1. Institute of Material Physics and Department of Physics; Huazhong University of Science & Technology; Wuhan 430074; China; 2. Structure Analysis Cente; University of Science and Technology of China; Hefei 230026; China
  • Received:2001-11-21 Revised:2002-04-19 Published:2003-01-20 Online:2003-01-20

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摘要： 报道了对La2/3Ca1/3MnO3和La2/3Ba1/3MnO3系统不同温度下的电子顺磁共振(EPR)实验研究,当温度高于某一特征温度Tmin时,共振线宽随温度降低而线性变窄;当温度低于Tmin时,共振线宽表现出反常展宽.基于“瓶颈(bottleneck)”自旋-晶格弛豫模型我们对这种行为进行了讨论,并且指出A位离子平均半径强烈影响着自旋-晶格交换作用和自旋-自旋相互作用的强弱.

关键词: 顺磁共振, 共振线宽, 瓶颈模型, 超大磁电阻效应

Abstract: The electron paramagnetic resonance spectra of La2/3Ca1/3MnO3 and La2/3Ba1/3MnO3 were
measured at various temperatures. It is show that there exists a temperature T min by which the conventional paramagnetic region of T>Tc
is divided into two different temperature ranges, T>Tmin and Tc<T<Tmin. At T>Tmin, the peak-to-peak linewidth
ΔHpp as a function of temperature shows a linear decrease on cooling, while at T<Tmin, ΔHpp is anomalously
increased on further cooling. The results can be explained by the “bottleneck” spin-lattice relaxation model. The average A-site ionic size <rA>
affects strongly the interaction of the spin-lattice and spin-spin.

Key words: EPR, linewidth, bottleneck model, CMR

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