Bond-versus site-centred ordering and possible ferroelectricity in manganites
Bond-versus site-centred ordering and possible ferroelectricity in manganites
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DOI：
10.1038/nmat1236
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发表时间：
2004-12-01
期刊：
影响因子：
41.2
通讯作者：
Khomskii, DI
中科院分区：
文献类型：
--
作者：
Efremov, DV;Van den Brink, J;Khomskii, DI
具有钙钛矿型结构的过渡金属氧化物构成了一大批具有有趣性质的化合物。其中包括典型的铁电系统BaTiO3、巨磁阻锰矿石和高温超导体等材料。这些化合物中有数百种是磁性的，还有数百种是铁电性的，但这些性质很少共存。磁性和铁电性相互依赖的化合物可能非常有用：它们将开辟大量的新应用，例如通过电场开关磁存储元件。在这里，我们报告了一种可能避免这种不相容的方法，并表明在电荷有序和轨道有序的钙钛矿中，可以利用磁性和电荷有序之间的耦合来获得铁电磁体。特别是，在掺杂量不到一半的锰矿石中，存在一种介于位中心和键中心之间的电荷顺序。这种状态打破了反转对称性，并被预测为磁性和铁电态。
Transition metal oxides with a perovskite-type structure constitute a large group of compounds with interesting properties. Among them are materials such as the prototypical ferroelectric system BaTiO3, colossal magnetoresistance manganites and the high-Tcsuperconductors. Hundreds of these compounds are magnetic, and hundreds of others are ferroelectric, but these properties very seldom coexist. Compounds with an interdependence of magnetism and ferroelectricity could be very useful: they would open up a plethora of new applications, such as switching of magnetic memory elements by electric fields. Here, we report on a possible way to avoid this incompatibility, and show that in charge-ordered and orbitally ordered perovskites it is possible to make use of the coupling between magnetic and charge ordering to obtain ferroelectric magnets. In particular, in manganites that are less than half doped there is a type of charge ordering that is intermediate between site-centred and bond-centred. Such a state breaks inversion symmetry and is predicted to be magnetic and ferroelectric.