Orbital order and fluctuations in Mott insulators
Orbital order and fluctuations in Mott insulators
复制标题
DOI：
10.1143/ptps.160.155
复制
发表时间：
2005-01-01
影响因子：
--
通讯作者：
Khaliullin, G
中科院分区：
文献类型：
--
作者：
Khaliullin, G
讨论了过渡金属氧化物中控制轨道有序和轨道涨落的基本机制。晶格驱动的经典轨道图像，例如在锰氧化物LaMnO 3中，与在伪立方钛酸盐ATIO（3）和钒酸盐AVO（3）中实现的受抑超交换模型中轨道的量子行为形成对比。在YVO 3中，晶格和超交换效应强烈竞争-这解释了磁状态对温度和掺杂的极端敏感性。以层状钴酸盐为例，考虑了相对论自旋轨道耦合对t（2g）轨道简并度的提升。我们发现，低能量状态的自旋轨道混合导致不寻常的磁相关在一个三角形晶格的CoO 2母体化合物。最后，讨论了富钠化合物Na 1-x，CoO 2的磁性的自旋/轨道极化液体。
Basic mechanisms controlling orbital order and orbital fluctuations in transition metal oxides are discussed. The lattice driven classical orbital picture, e.g. like in manganites LaMnO3, is contrasted to the quantum behavior of orbitals in frustrated superexchange models as realised in pseudocubic titanites ATiO(3) and vanadates AVO(3). In YVO3, the lattice and superexchange effects strongly compete - this explains the extreme sensitivity of magnetic states to temperature and doping. Lifting the t(2g) orbital degeneracy by a relativistic spin-orbital coupling is considered on example of the layered cobaltates. We find that the spin-orbital mixing of low-energy states leads to unusual magnetic correlations in a triangular lattice of the CoO2 parent compound. Finally, the magnetism of sodium-rich compounds Na1-x,CoO2 is discussed in terms of a spin/orbital polaronic liquid.