La_(1-x)Zn_xMnO_3和La_(2/3)Sr_((1-x)/3)Zn_(x/3)MnO_3的磁电输运特性

Magnetotransport Properties of La_(1-x)Zn_xMnO_3 and La_(2/3)Sr_((1-x)/3)Zn_(x/3)MnO_3 Compounds

用固相反应方法制备La1-xZnxMnO3和La2/3Sr（1-x）/3Znx/3MnO3化合物。La1-xZnxMnO3在不同掺杂浓度x的研究表明：Zn2＋在一定浓度范围内掺杂,具有钙钛矿结构,但掺杂浓度在50%-70%时有ZnO衍射峰,其电阻率在100 K以上随温度而下降,当掺杂浓度为x=0.3时电阻率最低。当Zn2＋和Sr2＋共掺而保持La3＋浓度不变,即载流子浓度不变,维持Mn3＋/Mn4＋=2：1,随Zn2＋掺杂浓度增大,铁磁-顺磁转变温度降低,磁阻效应增大。低场磁阻效应与Zn2＋掺杂浓度无关,而与温度有关;高场磁阻效应随掺杂浓度增大而增大。

The La1-xZnxMnO3 and La2/3 Sr（l-x）/3 Znx/3 MnO3 compounds were prepared by conventional solidstate reaction method. The study on La1-xZnxMnO3 compound shows that there exists perovskite structure in all doping contents while the diffraction peaks of ZnO appears when the doping content of Zn^2＋ is in the range of 50% -70%. The resistivity of these compounds decreases with increase of temperature. The resistivity of the compound with x =0.3 is lowest and the magnetic field have an obvious effect on the resistivity. However, the results of Zn^2＋ and Sr^2＋ codoping with the fixed Mn^/Mn^4＋ = 2 ： 1 ratio show that the peak resistivity and curie tra＋nsition temperature decrease while the magnetoresistance （MR） increases by increasing Zn^2＋ doping content. The low -field magnetoresistance（LFMR） remains unchanged while the high-field magnetoresistance increases by increasing Zn^2＋ doping content.