【摘要】 用四探针法对不同倾斜衬底LaAlO3 上的La0 .67Ca0 .3 3 MnO3 薄膜进行了不同电流下的电阻温度关系测试 ,发现了 3个结果 :①偏电流 >1mA时 ,焦耳热作用使电阻温度曲线的转变点温度下降 ;②偏电流 <1mA时 ,薄膜的转变点电阻随所加的偏电流的增加而减小 ,这是对欧姆行为的偏离 (即非欧姆行为 ) ;③这一偏离随衬底倾斜角度的增加而增加 .对经过氧气氛高温退火的La0 .67Ca0 .3 3 MnO3 薄膜进行了测量 ,发现峰值电阻及峰值电阻的变化明显减小 .初步分析的结果是 :①大电流的加热效应是峰值温度偏移 ;②可能是晶界作为隧穿结导致了薄膜中的非欧姆行为更多还原

【Abstract】 In this experiment,La_0.67Ca_0.33MnO₃ films grown on different canted LaAlO₃ substrates were tested with different bias currents.The results found are:① the temperature of the peak resistance decreases obviously due to the Joule heat effect when the current is lager than 1?mA;② the maximum resistance in R-T curves is reduced with the current increasing when the current is less than 1?mA.This is a deviation from the Ohm’s law（namely nonohmic behavior）;③ the nonohmic behavior become larger with the canted angle increasing.By analyzing,two results were obtained:① Joule heat effect causes the transit temperature T_M-I to decrease;② nonohm behavior in films is possibly caused by the grain boundries as tunneling resistance junctions.更多还原