La_(2/3)(Ca,Ba)_(1/3)MnO_3系统的顺磁共振研究  

Electron Paramagnetic Resonance Measurements of La_(2/3) (Ca,Ba)_(1/3)MnO_3

作　　者：彭刚[1] 袁松柳[1] 金嗣昭[2] 

机构地区：[1]华中科技大学物理系,武汉430074 [2]中国科技大学结构分析中心,合肥230026

出　　处：《无机材料学报》2003年第1期169-174,共6页Journal of Inorganic Materials

基　　金：国家自然科学基金(10174022);教育部"跨世纪优秀人才基金"

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.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 > T-c is divided into two different temperature ranges, T > T-min and T-c < T < T-min. At T > T-min, the peak-to-peak linewidth DeltaH(pp) as a function of temperature shows a linear decrease on cooling, while at T < T-min DeltaH(pp) is anomaJ.ously.increased on further cooling. The results can be explained by the 'bottleneck' spin-lattice relaxation model. The average A-site ionic size < r(A) > affects strongly the interaction of the spin-lattice and spin-spin.

关 键 词：顺磁共振 共振线宽 瓶颈模型 超大磁电阻效应 磁性 锰酸钙镧 锰酸钡镧 ABO3型钙钛矿型锰氧化物 

分 类 号：TM27[一般工业技术—材料科学与工程]