论文标题
在D-电子LATIO3,LAVO3,SRMNO3和LAMNO3 PEROVSKITE的D-Electron Latio3,Lavo3,Srmno3和Lamno3 perovskites中的绝缘带间隙作为对称性事件
Insulating band gaps both below and above the Néel temperature in d-electron LaTiO3, LaVO3, SrMnO3, and LaMnO3 perovskites as a symmetry-breaking event
论文作者
论文摘要
在被占用和空的带边缘状态中具有相同轨道特征的奇数电子的化合物预计将在费米能量处具有带堕落性,从而制造这种参考系统金属。然而,实际上,许多具有磁性3D B原子的ABO3氧化物钙钛矿实际上是低于和高于Neel温度的绝缘体。传统上,通过主要基于高阶电子效应(例如强电源互相关)(MOTT机制)来调用破坏性物理学(MOTT机制),从传统上解决了实验观察和期望之间的这些不一致之处。这种解释通常利用最高的对称结构,将微观自由度(M-DOF)视为很大程度上的被动观众。然而,长期以来,人们一直知道,Abo3钙钛矿可以以八面体倾斜,键二聚体,jahn-teller扭曲和局部磁矩的顺序表现出M-DOF的排列,这是稳定的内在对称性的一部分。局部实验探针和理论上的总能量最小化其出生的痴呆状态都可以看到这种M-DOF。虽然这种局部结构和磁对称性破坏基序通常被认为是在过渡到Para阶段下方参考系统间隙的原因,但通常也经常认为,这些局部图案可能消失的过渡上方,需要不同的机制来掩盖 - 例如强相关。在这里,我们检查了这种内在的结构和磁对称性破坏是否可能系统地解释在磁性转变下方和上方的绝缘带间隙的形成,并同时考虑了某些化合物中缺乏毛间隙的特定和非偶然的例外,例如SRVO3。
Compounds having an odd number of electrons with the same orbital character in occupied and unoccupied band edge states would be expected to have band degeneracy at the Fermi energy, making such reference system metals. Yet, many ABO3 oxide perovskites with a magnetic 3d B-atom are, in fact, insulators both below and above the Neel temperature. These inconsistencies between experimental observation and expectation have been traditionally resolved by invoking degeneracy-breaking physics based largely on high-order electron effects, such as strong interelectronic correlation (the Mott mechanism). Such explanations generally utilize the highest symmetry structure, considering microscopic degrees of freedom (m-DOF) as largely passive spectators. Yet, it has long been known that ABO3 perovskites can manifest an arrangement of m-DOFs in the form of octahedral tilting, bond dimerization, Jahn-Teller distortions, and ordering of local magnetic moments as part of the stabilizing intrinsic symmetry. Such m-DOFs are seen both by local experimental probes and theoretically in total energy minimization of its Born-Oppenheimer state. While such local structural and magnetic symmetry breaking motifs were often considered to be the reason for gapping of the reference system below the transition into Para phases, it was also often thought that above the transition those local motifs might vanish, requiring a different mechanism for gapping - such as strong correlation. Here we examine if such intrinsic structural and magnetic symmetry breaking might systematically explain the formation of insulating band gaps both below and above the magnetic transition and account at the same time for specific and non-accidental exceptions of the absence of gaping in some compounds, such as SrVO3.