Magnetic interaction in Mg, Ti, Nb doped manganites
Magnetic interaction in Mg, Ti, Nb doped manganites
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Mg、Ti、Nb 掺杂亚锰矿中的磁相互作用
DOI：
10.1140/epjb/e2002-00202-2
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发表时间：
2002
期刊：
影响因子：
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通讯作者：
A. Maignan
中科院分区：
文献类型：
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作者：
I. Troyanchuk;M. Bushinsky;H. Szymczak;K. Bärner;A. Maignan
通过制备La_（0.7）Sr_（0.3）（Mn_（1-x）Mex）O_3和La_（1-x）Sr_x（Mn_（1- x/2）Nb_x/2）O_3系列样品，研究了Mn在锰氧化物中的替代效应。结果表明，当Mn的取代量达到tox= 0.16时，样品的长程铁磁有序结构发生了破坏，而La 0.7Sr 0.3（Mn 3 + 0.85Nb 5 + 0.15 Nb O3）样品在T_c = 123 K时具有铁磁性质，并且在居里点以下表现出很大的磁电阻.对La_（0.7）Sr_（0.3）（Mn_（1-x）Mex）O_3和La_（1-x）Sr_x（Mn_（1- x/2）Nb_x/2）O_3进行了磁相图的计算。结果表明，Mn ~（3+）-O-Mn ~（3+）交换相互作用是铁磁性的，当Mn ~（4+）的含量增加到Mn ~（4+）总量的50%以上时，由于反铁磁性Mn ~（4+）-O-Mn ~（4+）和铁磁性Mn ~（3+）-O-Mn ~（4+）超交换相互作用的竞争，形成自旋玻璃态.
An effect of Mn substitution with Me=Mg2+, Ti4+, Nb5+in manganites has been investigated by preparing La0.7Sr0.3(Mn1-xMex)O3and La1-xSrx(Mn1 - x/2Nbx/2)O3series. It was established that substitution of manganese with magnesium up tox= 0.16 leads to a collapse of a long-range ferromagnetic order whereas La0.7Sr0.3(Mn3 +0.85Nb5 +0.15)O3is ferromagnet withTC= 123 K and exhibits a large magnetoresistance below Curie point despite an absence of four-valent manganese. Hypothetical magnetic phase diagrams are constructed for La0.7Sr0.3(Mn1-xMex)O3and La1-xSrx(Mn1 - x/2Nbx/2)O3. Our results show that Mn3+-O-Mn3+exchange interaction is ferromagnetic in the orbitally disordered manganites as well as an increase of Mn4+content above 50% from a total amount of manganese ions leads to formation of a spin glass state due to a competition between antiferromagnetic Mn4+-O-Mn4+and ferromagnetic Mn3+-O-Mn4+(Mn3+) superexchange interactions.