Inverted orbital polarization in strained correlated oxide films
Inverted orbital polarization in strained correlated oxide films
复制标题
应变相关氧化膜中的反转轨道极化
作者：
P. Rogge;R. Green;P. Shafer;G. Fabbris;A. Barbour;Benjamin M. Lefler;E. Arenholz;M. Dean;S. May
作者：Rogge， PC；绿色,RJ;沙佛,P;fabbri G;巴伯,我;Lefler BM;Arenholz E;院长,MPM;摘要：©2018美国物理学会。通过外延应变来控制价电子的轨道占用，以诱导新的功能特性，需要考虑局部键环境的变化如何影响费米能级的能带结构。利用同步辐射测量相关氧化物CaFeO3外延应变薄膜的x射线线性二色性，我们证明了Fe价电子的轨道极化与传统认识相反。虽然多重配体场理论分析证实了Fe三维轨道的能量顺序与先前报道的应变诱导行为一致，但我们发现名义上高能量轨道比低能量轨道更密集。我们将这种倒轨道极化归因于具有近填充带的化合物对应变的各向异性带宽响应。这些发现为应变诱导轨道极化的传统理解提供了一个重要的反例，并揭示了一种在相关氧化物中设计否则无法实现的轨道占用的方法。
Author(s): Rogge, PC; Green, RJ; Shafer, P; Fabbris, G; Barbour, AM; Lefler, BM; Arenholz, E; Dean, MPM; May, SJ | Abstract: © 2018 American Physical Society. Manipulating the orbital occupation of valence electrons via epitaxial strain in an effort to induce new functional properties requires considerations of how changes in the local bonding environment affect the band structure at the Fermi level. Using synchrotron radiation to measure the x-ray linear dichroism of epitaxially strained films of the correlated oxide CaFeO3, we demonstrate that the orbital polarization of the Fe valence electrons is opposite from conventional understanding. Although the energetic ordering of the Fe 3d orbitals is confirmed by multiplet ligand field theory analysis to be consistent with previously reported strain-induced behavior, we find that the nominally higher energy orbital is more populated than the lower. We ascribe this inverted orbital polarization to an anisotropic bandwidth response to strain in a compound with nearly filled bands. These findings provide an important counterexample to the traditional understanding of strain-induced orbital polarization and reveal a method to engineer otherwise unachievable orbital occupations in correlated oxides.