Stability of half-metallic antiferromagnet La2VMnO6, first-principles calculation study
Stability of half-metallic antiferromagnet La2VMnO6, first-principles calculation study
复制标题
DOI：
10.1016/j.physb.2011.04.028
复制
发表时间：
2011-07-15
影响因子：
2.8
通讯作者：
Wang, Y. K.
中科院分区：
文献类型：
--
作者：
Chen, S. H.;Xiao, Z. R.;Wang, Y. K.
Pickett等人基于第一性原理计算预测了具有Fm（3）over barm结构的双钙钛矿La 2 VMnO 6是半金属（HM）反铁磁体（AFM），而Androulakis等人基于第一性原理计算预测了具有Fm（3）over barm结构的双钙钛矿La 2 VMnO 6是半金属反铁磁体（AFM）。的实验结果表明，La 2 VMnO 6也表现出与亚铁磁（FiM）态相同的结构。为了深入理解具有Fm（3）over barm结构的双钙钛矿La 2 VMnO 6中发生的情况，我们首先计算了固定的立方Fm（3）over barm结构，然后通过优化过程重新计算结构。结果表明，La_2VM_nO_6在固定和体积弛豫的立方Fm（3）over barm结构中是一个FiM态.然而，在完全弛豫之后，它变成HM-AFM，并且即使考虑到现场库仑相互作用（+U）也保持相同的状态。计算结果表明，Mn离子的磁态对MnO 6八面体的晶场敏感，是La 2 VMnO 6完全弛豫后从FiM态转变为AFM态的主要原因.由于总能量Δ EFiM-AFM的差异很小（仅约57.1meV/f.u.）并且La_2VMnO_6在FiM态和AFM态下的空间群几乎相同，我们认为La_2VMnO_6在FiM态和AFM态下的空间群主要取决于MnO_6八面体的晶场，即MnO_6八面体的畸变大小，这与合成过程有关。虽然Androulakis et al.的实验结果表明，这是一个Fm（3）over barm/FiM态，我们认为14/mmm/AFM态仍有可能存在，即HM-AFM La_2VM_nO_6。(C)2011 Elsevier B. V.保留所有权利。
The double perovskite La2VMnO6 with a Fm (3) over barm structure was predicted by Pickett et al. as a half-metal (HM) antiferromagnet (AFM) based on first principle calculations, while Androulakis et al.'s experimental result showed that La2VMnO6 also exhibits the same structure as a ferrimagnetic (FiM) state. For thoroughly understanding what happens in the double perovskite La2VMnO6 with a Fm (3) over barm structure, we first calculated the fixed cubic Fm (3) over barm structure before recalculating the structure through an optimization process. Our results show that La2VMnO6 is a FiM state when found in the fixed and volume-relaxed cubic Fm (3) over barm structure. However, after full relaxation, it becomes a HM-AFM and remains the same state even on-site Coulomb interactions (+U) are taken into consideration. This recalculation illustrates that the magnetic state of the Mn ion is sensitive to the crystal field of MnO6 octahedron, and is the main reason behind the transformation of the magnetic state of La2VMnO6 from a FiM to a AFM state after full relaxation. Because the difference of total energy Delta EFiM-AFM is small (merely about 57.1 meV/f.u.) and shows up as nearly the same space group in both FiM and AFM states La2VMnO6, we conclude that in which state it is mainly determined by the crystal field of the MnO6 octahedron, i.e. the distortion magnitude of the MnO6 octahedron, which is related to the process of synthesis. Although Androulakis et al.'s experimental result show that this is a Fm (3) over barm/FiM state, we think that it is still possible for a 14/mmm/AFM state to exists, i.e. a HM-AFM La2VMnO6. (C) 2011 Elsevier B.V. All rights reserved.