FeTe中面向拓扑超导电性的电子重构
Electronic Reconstruction Towards Topological Superconductivity in FeTe
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- The Pennsylvania State University（宾夕法尼亚州立大学）
- University of Florida（佛罗里达大学）
- The University of Chicago（芝加哥大学）
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中文总结 AI 辅助
本研究通过多种实验与理论手段揭示FeTe薄膜在退火过程中的电子重构，确立其本征超导电子结构，并发现拓扑表面态与超导共存，为拓扑超导和马约拉纳束缚态研究提供平台。
中文摘要 AI 辅助
最近在化学计量比FeTe薄膜中发现本征超导电性，重新激发了人们对铁硫族化合物富碲端成员在非常规和拓扑超导电性研究中的兴趣，但其本征电子结构仍未得到解决。在本工作中，我们结合分子束外延、角分辨光电子能谱（ARPES）、电输运测量、密度泛函理论和嵌入动力学平均场理论，追踪了20个单胞厚的FeTe薄膜在碲退火逐步去除过量间隙铁并将系统从反铁磁金属驱动到超导体的过程中的电子重构。我们发现这一演化伴随着准粒子相干性的恢复、电子关联的减弱、Lifshitz转变和拓扑相变，产生了以dxy为主的空穴和电子口袋，有利于口袋间散射。此外，一个位于费米能级以下约2 meV的浅dxz/dyz衍生空穴带可能提供初始带配对通道，而M点处两个电子口袋之间的散射可能提供额外的配对通道。高分辨率的偏振依赖激光ARPES测量进一步揭示了一个拓扑表面态，其圆二色性与化学计量比FeTe的预期轨道角动量纹理一致。这些结果确立了超导FeTe的本征低能电子结构，并识别出与超导电性最相关的电子态。本征超导电性与拓扑表面态的共存使化学计量比FeTe成为探索拓扑超导电性和可能的马约拉纳束缚态的有前景平台。
英文摘要
The recent discovery of intrinsic superconductivity in stoichiometric FeTe films has renewed interest in the Te-rich end member of the iron chalcogenides for studies of unconventional and topological superconductivity, yet its intrinsic electronic structure remains unresolved. In this work, we combine molecular beam epitaxy, angle-resolved photoemission spectroscopy (ARPES), electrical transport measurements, density functional theory, and embedded dynamical mean-field theory to track the electronic reconstruction of 20-unit-cell FeTe films as Te annealing progressively removes excess interstitial Fe and drives the system from an antiferromagnetic metal to a superconductor. We find that this evolution is accompanied by recovered quasiparticle coherence, reduced electronic correlations, a Lifshitz transition, and a topological phase transition, yielding dxy-dominated hole and electron pockets that favor inter-pocket scattering. In addition, a shallow dxz/dyz-derived hole band located about 2 meV below the Fermi level may provide an incipient-band pairing channel, while scattering between the two electron pockets at M may offer additional pairing channels. High-resolution polarization-dependent laser ARPES measurements further reveal a topological surface state whose circular dichroism is consistent with the expected orbital-angular-momentum texture of stoichiometric FeTe. These results establish the intrinsic low-energy electronic structure of superconducting FeTe and identify the electronic states most relevant to superconductivity. The coexistence of intrinsic superconductivity and a topological surface state establishes stoichiometric FeTe as a promising platform for exploring topological superconductivity and possible Majorana bound states.
