Varignon Julien, Bibes Manuel, Zunger Alex
Unité Mixte de Physique, CNRS/Thales, Université Paris Sud, Université Paris-Saclay, 91767, Palaiseau, France.
University of Colorado Boulder Colorado, Boulder, CO, 80309, USA.
Nat Commun. 2019 Apr 10;10(1):1658. doi: 10.1038/s41467-019-09698-6.
With their broad range of properties, ABO transition metal perovskite oxides have long served as a platform for device applications and as a testing bed for different condensed matter theories. Their insulating character and structural distortions are often ascribed to dynamical electronic correlations within a universal, symmetry-conserving paradigm. This view restricts predictive theory to complex computational schemes, going beyond density functional theory (DFT). Here, we show that, if one allows symmetry-breaking energy-lowering crystal symmetry reductions and electronic instabilities within DFT, one successfully and systematically recovers the trends in the observed band gaps, magnetic moments, type of magnetic and crystallographic ground state, bond disproportionation and ligand hole effects, Mott vs. charge transfer insulator behaviors, and the amplitude of structural deformation modes including Jahn-Teller in low temperature spin-ordered and high temperature disordered paramagnetic phases. We then provide a classification of the four mechanisms of gap formation and establish DFT as a reliable base platform to study the ground state properties in complex oxides.
由于具有广泛的性质，ABO型过渡金属钙钛矿氧化物长期以来一直是器件应用的平台，也是不同凝聚态理论的试验场。它们的绝缘特性和结构畸变通常归因于通用的、对称性守恒范式内的动态电子关联。这种观点将预测理论限制在复杂的计算方案中，超出了密度泛函理论（DFT）的范畴。在此，我们表明，如果在DFT中允许对称性破缺的能量降低晶体对称性降低和电子不稳定性，就能够成功且系统地恢复观测到的带隙、磁矩、磁性和晶体学基态类型、键 disproportionation 和配体空穴效应、莫特与电荷转移绝缘体行为以及包括低温自旋有序和高温无序顺磁相中的 Jahn-Teller 在内的结构变形模式的幅度等趋势。然后，我们对带隙形成的四种机制进行了分类，并将DFT确立为研究复杂氧化物基态性质的可靠基础平台。
