Fe掺杂La0．8Sr0．2Co1-xFexO3磁性的研究

利用溶胶-凝胶法制备了一系列的La0.8Sr0.2Co1-xFexO3样品.通过研究在不同外加磁场下磁化强度和温度变化的关系发现,在较高的外场下La0.8Sr0.2Co1-xFexO3样品的磁性反转现象没有被观察到;在低场下La0.8Sr0.2Co1-xFexO3系统磁性反转现象被实现.这说明Fe的掺杂引起了La0.8Sr0.2Co1-xFexO3样品中铁磁和反铁磁之间的竞争,导致了La0.8Sr0.2Co1-xFexO3样品磁性反转;同时外加磁场的强弱影响了La0.8Sr0.2Co1-xFexO3系统磁性反转现象的发生,外加磁场增大使得在La0.8Sr0.2Co1-xFexO3样品中Co离子的自旋平行趋势更强,在铁磁和反铁磁之间的竞争中铁磁耦合占主导优势,因此在较高的外场下磁性反转现象没有被观察到.

THE STUDY OF MAGNETIC PROPERTIES IN Fe-doped La0.8Sr0.2CO1-xFexO3 SYSTEM

A series of La_(0.8)Sr_(0.2)Co_(1-x)Fe_xO_3 samples are prepared by sol-gel method. Magnetization reversal of La_(0.8)Sr_(0.2)Co_(1-x)Fe_xO_3 samples has not found in the high field but found in the low field with temperature dependence of magnetization. It is shown that Fe-doping induces the competition between ferromagnetism interaction(FM) of Co3 -O-Co4 and superexchange antiferromagnetism interaction(AFM) of Co3 -O-Fe3 and Co4 -O-Fe3 in La_(0.8)Sr_(0.2)Co_(1-x)Fe_xO_3 samples, which makes appearance of magnetization reversal. At the same time that the applied magnetic field affects the appearance of magnetization reversal, the more applied field leads to the more trends of Co ions spin parallel arrangement in La_(0.8)Sr_(0.2)Co_(1-x)Fe_xO_3 samples, so the magnetization reversal is not observed in the more applied field because of the FM domination during the competition between FM and AFM.