典型过渡金属双钙钛矿氧化物 Ca$_2$FeMnO$_6$ 中由配体空穴驱动的金属–绝缘体转变
Ligand hole driven metal-insulator transition in a prototypical transition metal double perovskite oxide Ca$_2$FeMnO$_6$
AI总结：
该研究结合 DFT 与扩展 Hubbard TB 模型，揭示 CFMO 的 MIT 源于 O-2p 配体空穴局域化引发的电荷歧化、Jahn-Teller 畸变及负电荷转移能，而非 Mott-Hubbard 作用。
摘要：
采用第一性原理密度泛函理论以及基于扩展 Hubbard 模型的紧束缚（TB）哈密顿量建模，研究了 Ca$_2$FeMnO$_6$（CFMO）双钙钛矿。电子结构分析表明，低温下的电荷有序和磁有序由电荷歧化驱动；这种歧化源于 O-$2p$ 配体空穴在交替 Fe 位点上的部分局域化，并产生 Jahn-Teller 畸变，从而导致 CFMO 中的金属–绝缘体转变（MIT）。结果表明，MIT 由自空穴掺杂的负电荷转移能触发，而负电荷转移能导致对称性降低的转变。值得注意的是，研究发现带隙本质上由电荷转移能的强度控制，而非由 Mott-Hubbard 相互作用控制；该机制可通过组分、压力或化学计量比调制进行建模。本工作提出的基础性认识将有助于理解其他类型钙钛矿和关联金属中的类似物理机制。
英文摘要：
Ca$_2$FeMnO$_6$ (CFMO) double perovskite was studied using first principles density functional theory and tight-binding (TB) Hamiltonian modeling using extended Hubbard model. We have shown by electronic structure analysis that charge- and magnetic-ordering are driven by charge disproportionation at low temperature caused by partial localization of O-$2p$ ligand holes at alternate Fe sites that creates Jahn-Teller distortion, which leads to metal to insulator transition (MIT) in CFMO. Our results suggests MIT was triggered by negative charge-transfer energy of self-hole doping, responsible for symmetry lowering transitions. Notably, the band-gap was found to fundamentally controlled by the strength of the charge-transfer energy, and not by the Mott-Hubbard interactions, which can be modeled by composition, pressure or stoichiometry modulations. The fundamental insights presented in this work will help understand similar physics and mechanisms in other class of perovskites and correlated metals.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
