La_(2/3)Ca_(1/3)MnO_3体系La位上Y掺杂及其对输运性质的影响  

Y-DOPING ON THE La SITES AND ITS EFFECTS OF ON TRANSPORT PROPERTIES IN La_(2/3)Ca_(1/3)MnO_3 SYSTEM

作　　者：杨应平[1] 李广[2] 姜勇[2] 曾祥勇[2] 李建青[1] 袁松柳[2] 

机构地区：[1]武汉汽车工业大学基础部,武汉430070 [2]华中理工大学物理系,武汉430074

出　　处：《低温物理学报》2000年第3期205-209,共5页Low Temperature Physical Letters

摘　　要：零场下 (La1 -xYx) 2 / 3 Ca1 / 3 MnO3 (0 <x<0 .2 )系统电阻温度关系测量表明 ,所有样品高温时呈半导体导电而低温时呈金属导电 ,半导体 金属转变随La位上Y掺杂而移向低温区域 ,伴随着转变温度的降低 ,转变温度附近的电阻峰值大大增加 .基于自旋 极化子理论 ,我们对实验观察进行了定量分析 ,结果表明 ,尽管理论预言了半导体 金属转变特征 ,但定量上理论预言和实验观察仍存在大的差别 ,这一差别随Y掺杂量的增加而逐渐变小 ,意味着自旋 极化效应随单电子eg 带的变窄而变得更为明显 .The measurements of resistance vs temperature dependence in zero magnetic field for (La\-\{1- x \}Y\- x )\-\{2/3\}Ca\-\{1/3\}MnO\-3(0< x <0.2)system show that all samples behave semiconductor like conduction at high temperatures and metallic conduction at low temperatures. Doping of Y on La sites makes the semiconductor metal transitions moves toward lower temperature region and the peak resistance near the transition temperature greatly enhance. Based on the spin polaron theory, a quantitative analysis is carried out. The results indicate that although the theory predicts the feature of the semiconductor metal transition, there is still a obvious difference between the theoretical calculation and the experimental measurements. Such a difference reduces gradually with Y doping, which means the effect of the spin polarization becomes more evident with the narrowing of the single electron e\-g band width.

关 键 词：钙钛矿结物 锰基氧化物 Y掺杂 输运性质 

分 类 号：O513[理学—低温物理]