Phase problem in the B-site ordering of La2CoMnO6: impact on structure and magnetism
Phase problem in the B-site ordering of La2CoMnO6: impact on structure and magnetism
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DOI：
10.1039/c5nr01642h
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发表时间：
2015-01-01
期刊：
影响因子：
6.7
通讯作者：
Moshnyaga, V.
中科院分区：
文献类型：
--
作者：
Egoavil, R.;Huehn, S.;Moshnyaga, V.
采用金属有机物气溶胶沉积法在SrTiO 3（111）衬底上生长了双钙钛矿La 2 CoMnO 6（LCMO）薄膜。高居里温度，T-C = 226 K，和接近饱和的大磁化强度，M-S（5 K）= 5.8 μ（B）/f.u.，表明膜内B位（Co，Mn）有序度为97%。通过扫描透射电子显微镜和能量色散X射线能谱（STEM-EDX）在原子尺度上直接成像Co/Mn有序。局部电子能量损失谱（EELS）的测量结果表明，B-网站主要是由Co2+和Mn 4+离子在定量协议与磁性数据。相对较小的值（1/2 1/2 1/2）的超结构峰强度，通过X射线衍射（XRD），指出存在的有序域与任意的相关系跨越域边界。这些域的大小估计是在35-170 nm的范围内，根据TEM观察和建模的磁化数据。这些观测结果提供了重要的信息，对阳离子有序现象的复杂性及其对双钙钛矿和类似材料的磁性的影响。
Epitaxial double perovskite La2CoMnO6 (LCMO) films were grown by metalorganic aerosol deposition on SrTiO3(111) substrates. A high Curie temperature, T-C = 226 K, and large magnetization close to saturation, M-S(5 K) = 5.8 mu(B)/f.u., indicate a 97% degree of B-site (Co,Mn) ordering within the film. The Co/Mn ordering was directly imaged at the atomic scale by scanning transmission electron microscopy with energy-dispersive X-ray spectroscopy (STEM-EDX). Local electron-energy-loss spectroscopy (EELS) measurements reveal that the B-sites are predominantly occupied by Co2+ and Mn4+ ions in quantitative agreement with magnetic data. Relatively small values of the (1/2 1/2 1/2) superstructure peak intensity, obtained by X-ray diffraction (XRD), point out the existence of ordered domains with an arbitrary phase relationship across the domain boundary. The size of these domains is estimated to be in the range 35-170 nm according to TEM observations and modelling the magnetization data. These observations provide important information towards the complexity of the cation ordering phenomenon and its implications on magnetism in double perovskites, and similar materials.