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La2 / 3 Ca1/ 3 MnO3 系统中Mn位上Cu掺杂效应通过测量其结构和输运性质而得以研究 .结果表明 ,尽管Cu掺杂未引起晶体结构的变化 ,但输运性质却发生了明显改变 ,未掺杂样品在～ 2 6 0K附近出现的由半导体到金属的相变随着掺杂量的增加而逐渐被抑制 ,取而代之的是低温下出现新的相变 .液氮温度下磁电阻测量表明 ,适当的Cu掺杂可导致磁电阻效应比的实质性提高
The Cu doping effect on the Mn site in La2 / 3 Ca1 / 3 MnO3 system was investigated by measuring its structure and transport properties. The results show that although the Cu doping did not cause the change of crystal structure, the transport properties were obvious The phase transition from the semiconductor to the metal in the vicinity of -260K is gradually suppressed with the increase of the doping amount and replaced by the new phase transition at low temperature.The magnetic resistance Measurements show that proper doping of Cu results in a substantial increase in the magnetoresistance effect ratio