Slater绝缘体磁性和电子结构的第一性原理研究

First-Principles Study on Magnetism and Electronic Structures of Slater Insulators

摘要: Slater相变是一种由于反铁磁序形成而导致的金属–绝缘体相变。本文采用第一性原理密度泛函计算方法研究了两种Slater绝缘体材料NaOsO₃和Cd₂Os₂O₇的电子结构，进而研究了反铁磁序排列、自旋轨道耦合和电子关联对其电子结构以及相变性质的影响。研究结果表明，非磁相NaOsO₃的具有金属性；而G型线性反铁磁结构是驱动NaOsO₃发生Slater相变的磁基态。此外，研究结果表明，非磁相的焦绿石Cd₂Os₂O₇的能带结构在费米能级处是连续的，表现为金属性；并且带有磁阻挫的Cd₂Os₂O₇发生Slater相变的条件十分苛刻，只有在自旋轨道耦合和1.8 eV电子关联的共同作用下一种全进–全出非线性反铁磁结构才能使其发生Slater相变。说明全进–全出非线性反铁磁结构是使Cd₂Os₂O₇发生Slater相变的磁基态，而自旋轨道耦合和1.8 eV的电子关联在消除磁阻挫上起到了关键作用。

Abstract: The Slater transition is one of the metal-insulator transitions that occur due to the formation of an antiferromagnetic order. In this dissertation, we use ab initio package to study the electronic structures of two Slater insulator materials, NaOsO₃ and Cd₂Os₂O₇, including electron energy bands and density of states by using the first-principle density functional calculation method. Furthermore, the effects of antiferromagnetic order, spin-orbit coupling (SOC) and electron cor-relation on the electronic structures and transition properties were investigated. We find that the electronic structures of NaOsO₃ in the non-magnetic phase are continuous and showing the behavior of metal; while the G-type antiferromagnetic structure changes the electronic structures of NaOsO₃, resulting in Slater transition. We find that the electronic structures of Cd₂Os₂O₇ in the non-magnetic phase are continuous and showing the behavior of metal. The conditions for the occurrence of Slater transition in frustrated Cd₂Os₂O₇ are very severe. Only the noncollinear all-in-all-out antiferromagnetic structure with the spin-order interactions and 1.8 eV electron correlation can cause the Slater transition. It shows that the noncollinear all-in-all-out antiferromagnetic structure is the magnetic ground state of Slater transition, and the spin-orbit coupling and the 1.8 eV electron correlation play a key role in eliminating the magnetic frustration.