标题： 新铁磁材料 FeCr$_3$Te$_6$ 中的 II 型 Weyl 节点、平带以及拓扑霍尔效应的证据 显示英文标题

标题： Type-II Weyl nodes, flat bands, and evidence for a topological Hall-effect in the new ferromagnet FeCr$_3$Te$_6$

摘要： 例如，在锯齿形铁磁体中，线性色散或狄拉克-like 电子能带和平坦电子能带之间的相互作用引起了人们的关注，这是由于拓扑结构与电子关联之间可能存在相互作用。 在这里，我们报道了一种单晶铁磁化合物的合成、结构、电学和磁学性质，即Fe$_{1/3}$CrTe$_2$或 FeCr$_3$Te$_6$，它结晶于$P\bar{3}m1$空间群，而不是之前报道的FeCr$_2$Te$_4$所属的$I2/m$空间群。 电子能带结构计算揭示了II类Dirac节点以及费米能级附近相对平坦的能带（$\varepsilon_F$）。 这种化合物显示出居里温度的开始点为$T_{\text{c}}\simeq 120$ K，随后在接近$T_{\text{c2}} \sim 92.5 $ K处发生一次额外的铁磁转变。在低于$T_{\text{c}}$ K时，FeCr$_3$Te$_6$显示出显著的异常霍尔效应，以及在低$T$时超过$\mu_0H = 1$~T的巨大矫顽场。然而，缩放分析表明，异常霍尔效应来源于重要的内在贡献，正如计算所预期的那样，但也来自外在机制，即散射。 外在贡献可能源于范德瓦尔斯间隙内1b铁位点的职业无序（在CrTe$_2$主体中）。我们还观察到拓扑霍尔分量叠加在整个霍尔响应之上，这表明在此中心对称系统中存在类似于斯格明子的手性自旋织构。它们的存在需要实验验证。 显示英文摘要

摘要： The interplay between linearly dispersing or Dirac-like, and flat electronic bands, for instance, in the kagome ferromagnets, has attracted attention due to a possible interplay between topology and electronic correlations. Here, we report the synthesis, structural, electrical, and magnetic properties of a single-crystalline ferromagnetic compound, namely Fe$_{1/3}$CrTe$_2$ or FeCr$_3$Te$_6$, which crystallizes in the $P\bar{3}m1$ space group instead of the $I2/m$ previously reported for FeCr$_2$Te$_4$. Electronic band structure calculations reveal type-II Dirac nodes and relatively flat bands near the Fermi level ($\varepsilon_F$). This compound shows onset Curie temperature $T_{\text{c}}\simeq 120$ K, followed by an additional ferromagnetic transition near $T_{\text{c2}} \sim 92.5 $ K. Below $T_{\text{c}}$, FeCr$_3$Te$_6$ displays a pronounced anomalous Hall effect, as well as sizable coercive fields that exceed $\mu_0H = 1$~T at low $T$s. However, a scaling analysis indicates that the anomalous Hall effect results from a significant intrinsic contribution, as expected from the calculations, but also from the extrinsic mechanism, i.e., scattering. The extrinsic contribution probably results from occupational disorder at the 1b Fe-site within the van der Waals gap of the CrTe$_2$ host. We also observe evidence for a topological Hall component superimposed onto the overall Hall response, suggesting the presence of chiral spin textures akin to skyrmions in this centrosymmetric system. Their possible presence will require experimental confirmation.