La0.67Ca0.33MnO3-δ体材料的巨磁电阻特性

La_0.67Ca_0.33MnO_3-δ体材料的巨磁电阻特性

摘要: 利用高温烧结法制备了多晶立方结构的La_0.67Ca_0.33MnO_3－δ体材料。材料的居里温度（T_C）为280K，其金属半导体转变温度（T_p）为270K，接近于T_C。外加磁场下的磁电阻（MR）峰值温度与T_p十分接近。外加磁场为0.6T和5T时，材料的MR峰置分别达到40%和76%。材料具有显著的巨磁电阻效应。在液氮温度附近，也观察到了相当大的磁电阻效应。

Abstract: Cubic polycrystalline bulk materials of La_0.67Ca_0.33MnO_3-δ were synthesized by sintering at high temperature. The samples showed a metal semiconductor transition at 270K, which was close to their Curie temperature, T_C , 280K. The magnetoresistance （MR） peak temperature appeared at the temperature very close to T_p. The MR peak value reached 76% under 5·10⁴Oe field, and still reached 40% under a low field of 6·10³Oe, both indicating a notable giant magnetoresistance （GMR） effect. There still existed relatively large MR effect at low temperatures near 77K, which was related to the transport behavior of the carriers near the grain boundaries.