类钙钛矿化合物Ca（Mn2Cu1）Mn4O12的磁性与磁电阻效应

利用固相反应法制备了名义成分为Ca(Mn2Cu1)Mn4O12的类钙钛矿锰氧化物.x射线衍射表明，为了获得较为致密的样品和减小杂相含量，可以采用高温烧结再在1073K长时间空气中退火的制备方法.样品在低温下同时存在铁磁相和反铁磁相，由于反铁磁相的存在导致样品在4.5K时的磁化强度显著降低，并在8T的高磁场下仍未达到饱和.样品呈半导体导电性质，在85K和6T磁场下磁电阻比的最大值可达-46%. 关键词： ［AC3］(B4)O12类钙钛矿锰氧化物 庞磁电阻效应 铁磁性 反铁磁性

Magnetic properties and colossal magnetoresistance effect in perovskite-type manganite Ca(Mn2Cu1)Mn4O12

The perovskite type manganites Ca(Mn2Cu1)Mn4O12 were prepared using the conventional solid state reaction method. X-ray diffraction patterns show that the annealing in air at 1073 K after the first sintering at higher temperatures can reduce the volumetric percentage of impurity phases in samples. Magnetic measurements indicate that the samples exhibit ferromagnetic antiferromagnetic transitions at low temperatures. Magnetization of the samples at 4.5 K is greatly decreased due to the existence of the antiferromagnetic phase, and shows no sign of saturation at 4.5 K and a magnetic field up to 8 T. The samples show semiconducting behavior. Their MR ratio reaches -35%—-46% at the temperature of 85 K and the magnetic field of 6 T.