标题： 退火的Kagome磁体FeGe在电荷密度波转变过程中的带结构重构的光学证据 显示英文标题

标题： Optical evidence of the band reconstruction during the charge-density wave transition in annealed Kagome magnet FeGe

摘要： 在Kagome磁体FeGe中，电子关联、电荷密度波（CDW）和磁性的共存使其成为研究它们相互作用的理想体系。 在这里，我们结合了光谱学和第一性原理计算来研究在不同温度退火的FeGe的能带结构。 我们的观察结果表明，320C退火的样品在CDW转变后光学电导率发生了显著变化。 具体来说，低能区（< 0.4 eV）的谱权重（SW）大量转移到高能区（0.8 - 1.5 eV），表明能带结构发生了重构。 在560C退火的样品中没有出现CDW转变，但其SW转移从300K到5K逐步发生。我们注意到：i）CDW转变后，320C退火的样品表现出与560C退火样品相似的SW转移趋势；ii）两种材料的高能SW都表现出与磁性性质一致的温度依赖性。 结合第一性原理计算，我们将SW转移归因于由560C退火或CDW转变引起的Ge1原子畸变所触发的能带重构。 这种晶格畸变影响了Fe 3d轨道的能量。 在Hund规则耦合的影响下，Fe原子的磁矩得到增强。 我们的发现阐明了FeGe中电荷、晶格和自旋之间的相互作用，为调节这种Kagome磁体的性质提供了关键见解。 显示英文摘要

摘要： In Kagome magnet FeGe, the coexistence of electron correlation, charge-density wave (CDW), and magnetism renders it ideal to study their interactions. Here, we combined the optical spectroscopy and the first-principles calculations to investigate the band structures of FeGe annealed at different temperatures. Our observations reveal that the sample annealed at 320C experienced dramatic change in optical conductivity following the CDW transition. Specifically, a substantial portion of the spectral weight (SW) in the low-energy region ( < 0.4 eV) was redistributed to the high-energy region (0.8 - 1.5 eV), suggesting a reconstruction of the band structure. The sample annealed at 560 C did not exhibit a CDW transition, but its SW transfer occurred progressively from 300 to 5 K. We noticed that: i) after the CDW transition, the sample annealed at 320 C showed similar tendency of SW transfer to that of the 560 C annealed sample; ii) the high-energy SW of both materials displayed a temperature dependence consistent with the magnetic roperties. Combining the first-principles calculations, we attribute the SW transfer to the band reconstruction triggered by the distortion of Ge1 atoms induced either by annealing at 560C or by the CDW transitions. This lattice distortion affects the energies of Fe 3d orbitals. Under the influence of Hund's rule coupling, the magnetic moment of Fe atoms is enhanced. Our findings elucidate the interactions among charge, lattice, and spin in FeGe, offering pivotal insights to modulate properties of this Kagome magnet.