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研究了用溶胶－凝胶（ｓｏｌ－ｇｅｌ）方法在 ＬａＡｌＯ_３（１００）衬底上制备的Ｌａ_（１－ｘ）Ｃａ_ｘＭｎ_（１．０３）Ｏ_３ 外延薄膜的磁电阻效应．ｘ在０．２～０．６２１范围内变化，外延薄膜的电阻率与温度的关系从类半导体行为 向金属导电行为转变，在ｘ≥０．５的４个样品中没有发现电荷有序绝缘体（ＣＯＩ）和反铁磁绝缘体（ＡＦＩ） 现象．ｘ＝０．２样品在１．５Ｔ磁场下磁电阻率 ＭＲ的最大值为１０~４％、磁转变温度为２３０Ｋ．
The magnetoresistance effect of La_ (1-x) Ca_xMn_ (1.03) O_3 epitaxial thin films deposited on LaAlO_3 (100) substrate by sol-gel method was studied. x varies from 0.2 to 0.621. The relationship between the resistivity and temperature of the epitaxial thin films changes from the behavior of semiconductors to that of metals. No charge-ordered insulator is found in the four samples with x≥0.5 COI) and antiferromagnetic insulator (AFI) phenomenon. The sample with x = 0.2 has a maximum MR of 10 ~ 4% at 1.5T and a magnetic transition temperature of 230K.