Abnormal electric transport property and magnetoresistance stability of La-Sr-K-Mn-O system  

作　　者：Yong-Gang Tang Gui-Ying Wang Guo-Qing Yan Qi-Xiang Song Ming-Yu Zhang Zhen-Sheng Peng 

机构地区：[1]Cultivating Base of Anhui Key Laboratory of Spintronics and Nano-materials Research [2]School of Mechanical and Electronic Engineering, Suzhou University

出　　处：《Rare Metals》2013年第3期258-263,共6页稀有金属（英文版）

基　　金：financially supported by the National Natural Science Foundation of China (No. 19934003);the Key Program of Natural Science Foundation of Anhui Province (Nos. KJ2011A259 and KJ2013A245);the Program of Professors and Doctors' Research Startup Foundation of Suzhou College (Nos. 2011jb01 and 2011jb02);the Program of Cultivating Base of Anhui Key Laboratory of Spintronics and Nano-materials Research (No. 2012YKF09)

摘　　要：The perovskite samples La1-x（Sr1-yKy）xMnO3 （y = 0.0, 0.2, 04, 0.6, 0.8） were prepared by the solid-state reaction method with comparatively low sintering tem- perature and with comparatively short sintering time, and the electric transport property and temperature stability of MR of this system were studied. The p-T curves show the abnormal phenomenon that with the increase of K doping amount, resistivity increases, and the insulator-metal transition temperature decreases, which is because the influence of the occupation disorder degree of A-site ions σ2 on the electric transport property of perovskite manga- nites is larger than that of the radius of A-site ions （rA）. In the temperature range below 225 K, MR increases contin- uously with the decrease of temperature, which is the characteristic of low-field magnetoresistance; in the com- paratively wide temperature range near 250 K, the MR- T curves of all the samples are comparatively fiat, and the value of MR almost does not change with temperature, which shows the temperature stability of magnetoresis- tance, and can be explained by the competition between the low-field magnetoresistance induced by spin-dependent tunneling of surface phase and the intrinsic magnetoresis- tance of grain phase. The magnetoresistance value of the sample with y = 0.8 keeps at （7.92 ±0.36） % in the very wide temperature range of 225-275 K, and this is a goodreference for the preparation of this kind of sample with practical application value in the future.The perovskite samples La1-x（Sr1-yKy）xMnO3 （y = 0.0, 0.2, 04, 0.6, 0.8） were prepared by the solid-state reaction method with comparatively low sintering tem- perature and with comparatively short sintering time, and the electric transport property and temperature stability of MR of this system were studied. The p-T curves show the abnormal phenomenon that with the increase of K doping amount, resistivity increases, and the insulator-metal transition temperature decreases, which is because the influence of the occupation disorder degree of A-site ions σ2 on the electric transport property of perovskite manga- nites is larger than that of the radius of A-site ions （rA）. In the temperature range below 225 K, MR increases contin- uously with the decrease of temperature, which is the characteristic of low-field magnetoresistance; in the com- paratively wide temperature range near 250 K, the MR- T curves of all the samples are comparatively fiat, and the value of MR almost does not change with temperature, which shows the temperature stability of magnetoresis- tance, and can be explained by the competition between the low-field magnetoresistance induced by spin-dependent tunneling of surface phase and the intrinsic magnetoresis- tance of grain phase. The magnetoresistance value of the sample with y = 0.8 keeps at （7.92 ±0.36） % in the very wide temperature range of 225-275 K, and this is a goodreference for the preparation of this kind of sample with practical application value in the future.

关 键 词：Keywords Magnetoresistance K doping Disorder degree σ2 Electric transport property 

分 类 号：O482.5[理学—固体物理]