Study on Electrical and Magnetic Properties of LCMO/SBT Composites

Study on Electrical and Magnetic Properties of LCMO/SBT Composites
　　Manganese pervoskite rare-earth oxides have been the hot topic for recent years, due to the potential application on magnetic storage, and magnetic sensor and so on. The colossal magnetoresistance is the common character of this kind of materials.Manganites are typical strongly correlated electron systems, spin, and charge, and orbital freedom degrees of coupling are crucial to the characters. The classical theories that neglect some interactions on studying the properties of Alnico magnets manganites do not work any more. So to understand the mechanism of CMR in manganites is a main challenge in condensed matter physics.In this paper, we mainly talk about the work done by me as a master during the recent two years.
　　The contents include four sections: firstly introducing the situation about the development of rare earth manganites, secondly telling the samples preparing and measuring methods, thirdly analyzing the results of measurement and summarizing the meaning in application generally, and fourthly describing the mechanism of measurement system designed by ourselves in high temperature region.We prepared the (La0.67Ca0.33MnO3 )1-x/(SrBi2Ta2O9)x (x=0%,1.5%,2%,3%,5%,7%,10%,15%,20%,25%) by conventional solid-state reaction. The electrical and http://www.999magnet.com/ magnetic transport properties were investigated systemically. It is interesting to note that with increasing SrBi2Ta2O9 (SBT) dopant, the change trend of the resistivity is different. When in low dopant, the resistivity increases as the SBT addition. When SBT reaches up to a certain value the resistivity decreases with increasing the dopant contents. However, the trend is not remained and changed as x>25%. The temperature transition of ferromagnetic-paramagnetic shifts to low temperature region and the magnetoresistance (MR) increases with the adding of dopant. But we still assume that MR won’t be keep increasing continually and there must be a maximal value.