FeO的量子临界相跨越地球下地幔的条件
Quantum critical phase of FeO spans conditions of Earth's lower mantle
AI总结：
本研究利用eDMFT方法发现FeO在地球下地幔条件下发生轨道选择性绝缘体-金属转变，处于具有中等电导率的量子临界状态，影响核幔电磁相互作用。
摘要：
地球内部主要由绝缘的岩石地幔和以金属铁为主的地核组成。最近的研究表明，核幔边界处的山脉尺度结构可能高度富集FeO，据报道FeO在极端压力-温度（P-T）条件下表现出高电导率和金属行为。然而，FeO中潜在的电子过程仍然知之甚少且存在争议。在这里，我们使用最先进的嵌入式动态平均场理论（eDMFT）进行大规模理论建模，系统地探索了B1-FeO在极端条件下的电子结构。对超过350个体积-温度条件下的相图进行精细采样表明，压缩FeO在高温下并非发生急剧金属化，而是诱导了逐渐的轨道选择性绝缘体-金属转变。具体而言，在下地幔的P-T条件下，FeO处于一种中间的“量子临界”状态，这是强关联电子物质的典型特征。该状态下的输运机制不同于绝缘或金属行为，其特征是导电的t_{2g}轨道中电子的非相干扩散和e_g轨道中的带隙，从而产生了中等电导率（~10^5 S/m），且对P-T仅有适度依赖，正如实验中所观察到的那样。因此，地球最下地幔中富FeO的区域可能会影响地幔与地核之间的电磁相互作用，从而产生在地球自转和磁场演化中观察到的若干特征。
英文摘要：
Earth's interior consists primarily of an insulating rocky mantle and a metallic iron-dominant core. Recent work has shown that mountain-scale structures at the core-mantle boundary may be highly enriched in FeO reported to exhibit high conductivity and metallic behavior at extreme pressure-temperature (P-T) conditions. However, the underlying electronic processes in FeO remain poorly understood and controversial. Here we systematically explore the electronic structure of B1-FeO at extreme conditions with large-scale theoretical modeling using state-of-the-art embedded dynamical mean field theory (eDMFT). Fine sampling of the phase diagram at more than 350 volume-temperature conditions reveals that, instead of sharp metallization, compression of FeO at high temperatures induces a gradual orbitally selective insulator-metal transition. Specifically, at P-T conditions of the lower mantle, FeO exists in an intermediate "quantum critical" state, characteristic of strongly correlated electronic matter. Transport in this regime, distinct from insulating or metallic behavior, is marked by incoherent diffusion of electrons in the conducting t_{2g} orbital and a band gap in the e_g orbital, resulting in moderate electrical conductivity (~ 10^5 S/m) with modest P -T dependence as observed in experiments. FeO-rich regions in Earth's lowermost mantle could thus influence electromagnetic interactions between the mantle and the core, producing several features observed in Earth's rotation and magnetic field evolution.
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