标题： 光谱学证据显示3$d$范德华铁磁体中的Kondo共振 显示英文标题

标题： Spectroscopic evidence of Kondo resonance in 3$d$ van der Waals ferromagnets

摘要： 二维范德华（vdW）铁磁体推动了自旋电子学应用的发展，并促进了在低维系统中奇异磁性的探索。 双$-$局域和巡游$-$电子性质的纠缠是关联电子系统的核心，导致了复杂的磁性、重费米子行为、Kondo晶格形成等奇异基态特性，\textit{等等}。 通过温度依赖的vdW铁磁体电子结构，(Co$_{x}$Fe$_{1-x}$)$_{3}$GeTe$_{2}$，使用高分辨率光电子能谱和密度泛函理论结合动力平均场理论（DFT+DMFT）进行探测，我们提供了由局域和巡游电子之间复杂相互作用驱动的Kondo共振峰出现的直接证据。 总体上与实验电子结构和磁性性质一致，DFT+DMFT还揭示了在$T_{C}$以外的有限自旋带分裂。 核心能级、价带光电子能谱以及DFT+DMFT谱函数显示在$T_{C}$范围内变化不显著，表明在(Co$_{x}$Fe$_{1-x}$)$_{3}$GeTe$_{2}$中存在非斯通纳磁性。 我们的结果为理解电子结构、奇特磁性和重费米子行为之间的复杂相互作用提供了新的途径，这种相互作用导致了3$d$层状范德华铁磁体中的Kondo效应。 显示英文摘要

摘要： Two-dimensional van der Waals (vdW) ferromagnets drive the advancement in spintronic applications and enable the exploration of exotic magnetism in low-dimensional systems. The entanglement of dual $-$ localized and itinerant $-$ nature of electrons lies at the heart of the correlated electron systems giving rise to exotic ground state properties such as complex magnetism, heavy fermionic behavior, Kondo lattice formation, \textit{etc}. Through temperature-dependent electronic structure of vdW ferromagnets, (Co$_{x}$Fe$_{1-x}$)$_{3}$GeTe$_{2}$, probed using high-resolution photoemission spectroscopy and density functional theory combined with dynamical mean field theory (DFT+DMFT), we provide direct evidence of the emergence of Kondo resonance peak driven by complex interplay between localized and itinerant electrons. In overall agreement with experimental electronic structure and magnetic properties, DFT+DMFT also reveals finite spin band splitting well beyond $T_{C}$. Core levels, valence band photoemission spectra together with DFT+DMFT spectral functions reveal insignificant change across $T_{C}$ indicating non-Stoner magnetism in (Co$_{x}$Fe$_{1-x}$)$_{3}$GeTe$_{2}$. Our results provide a way forward to the understanding of complex interplay between electronic structure, exotic magnetism and heavy fermionic behavior leading to Kondo scenerio in 3$d$ vdW ferromagnets.