Ag掺杂类钙钛矿Ca(Mn_2Cu_1)Mn_4O_(12)的电磁性能

Magnetic and Electronic Transport Properties in Ag Doped Ca(Mn_2Cu_1)Mn_4O_(12) Polycrystalline Perovskite Manganites

采用固相反应法制备了系列Ca(Mn2Cu1)Mn4O12/mAg2O多晶类钙钛矿锰氧化物。X射线衍射表明,m≤0.3的样品呈比较纯净的类钙钛矿相,而m>0.3的样品,是由类钙钛矿和金属Ag相组成的复合物。所有样品呈现半导体导电性质,电阻率低于未掺杂的Ca(Mn2Cu1)Mn4O12样品。居里温度测量表明,随着Ag掺杂量的增加,样品的居里温度逐渐升高。对于m=0.3和m=0.6的样品,120K温度和1T磁场下磁电阻比可达-10%左右。

Microstructure, magnetic and transport properties of the inhomogeneous system Ca（ Mn2Cu1 ） Mn4O12/mAg2O （ 1/m is molar ratio） have been studied. X - ray diffraction pattems show that the structure is a single perovskite phase for m 〈 0.3 samples and there are two - phase composite （perovskite phase and a nonmagnetic metal Ag phase） for m 〉 0.3 samples. The room temperature magnetoresistance （MR） effect is enhanced significantly due to the addition of Ag. For the m =0.3 and 0.6 samples the MR ratios reach -10% under a lower field of 1 T at the tempera- ture of 120 K. The effect is discussed qualitatively by use of spin - dependent scattering effects at grain boundaries.