Jeng Horng-Tay, Guo G Y, Huang D J
Physics Division, National Center for Theoretical Sciences, Hsinchu 300, Taiwan.
Phys Rev Lett. 2004 Oct 8;93(15):156403. doi: 10.1103/PhysRevLett.93.156403. Epub 2004 Oct 5.
Local density approximation + Hubbard U (LDA + U) band structure calculations reveal that magnetite (Fe3O4) forms an insulating charge-orbital-ordered state below the Verwey transition temperature. The calculated charge ordering is in good agreement with that inferred from recent experiments. We found an associated t(2g) orbital ordering on the octahedral Fe2+ sublattice. Such an orbital ordering results primarily from the on-site Coulomb interaction. This finding unravels such fundamental issues about the Verwey transition as the mechanism for the charge ordering and for the formation of the insulating gap, as well as the nonobedience of the Anderson's criterion for the charge ordering.
局域密度近似 + 哈伯德U（LDA + U）能带结构计算表明，磁铁矿（Fe3O4）在韦尔韦转变温度以下形成绝缘的电荷 - 轨道有序态。计算得到的电荷有序与近期实验推断的结果吻合良好。我们发现八面体Fe2+亚晶格上存在相关的t(2g)轨道有序。这种轨道有序主要源于在位库仑相互作用。这一发现揭示了关于韦尔韦转变的一些基本问题，如电荷有序的机制、绝缘能隙的形成，以及电荷有序对安德森准则的不遵循。
