Co和Cr掺杂对层状钙钛矿锰氧化物La_(1.2)Sr_(1.8)Mn_2O_7磁性的影响

EFFECT OF Co AND Cr SUBSTITUTION ON THE MAGNETIC PROPERTIES OF LAYERED PEROVSKITE MANGANESE OXIDE La_(1-2)Sr_(1-8)Mn_2O_7

研究了层状钙钛矿锰氧化物Ｌａ１－２Ｓｒ１－８ Ｍｎ２Ｏ７ 中Ｍｎ 被Ｃｏ 和Ｃｒ 替代对磁性能的影响．Ｃｏ 替代Ｍｎ 后，长程铁磁序被破坏，铁磁性减弱，出现团簇玻璃态和自旋玻璃态，表明Ｃｏ 离子和Ｍｎ 离子之间不存在双交换作用．而Ｍｎ 被Ｃｒ 替代后长程铁磁序仍然保持，证实Ｃｒ３ ＋ 和Ｍｎ３ ＋ 之间存在铁磁性交换作用．

The effect of substituting Mn by Co and Cr on the magnetic properties of layered perovskite manganese oxide La\-\{1.2\}Sr\-\{1.8\}Mn\-2O\-7 is investigated. Co doping results in the frustration of long\|range ferromagnetic (FM) order, weakening of ferromagnetism, and occurring of cluster\|glass and spin\|glass state, indicating that no double\|exchange interaction occurs between Co and Mn ions. However, the long\|range FM order still exists as Mn is replaced by Cr, which verifies that there is FM interaction between Mn\+\{3+\} and Cr\+\{3+\}.