Slater绝缘体的磁性和能带计算研究

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NaOsO_3和Cd_2Os_2O_7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,非磁相的NaOsO_3具有金属性;而G型线性反铁磁结构是驱动NaOsO_3发生Slater相变的磁基态.此外,研究结果表明,非磁相的焦绿石Cd_2Os_2O_7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Cd_2Os_2O_7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Cd_2Os_2O_7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.

Calculation Study on Magnetic and Band Structures in Slater Insulators

The Slater transition is one of the metal-insulator transition that occurs due to the formation of an antiferromagnetic order. In this dissertation, We using 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 correlation on the electronic structures and transition properties were investigated. We find that the electronic structures of NaOsO3 in the non-magnetic phase is 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 is continuous, and showing the behavior of metal. The conditions for the occurrence of Slater transition in frustrated Cd2Os2O7 very severe. Only the noncollinear all-in-all-out antiferromagnetic structure with the spin-order interactions and 1.8 eV electron correlation can causes 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