双层 kagome 铁磁体 Co$_3$Sn 的本征反常霍尔响应
Intrinsic anomalous Hall response in the bilayer kagome ferromagnet Co$_3$Sn
AI总结：
该研究制备出未合成过块体的 kagome 金属 Co$_3$Sn 高质量薄膜，证实其为室温 kagome 铁磁体，发现其反常霍尔响应源于费米能级附近的本征贝里曲率热点，明确层堆垛顺序对其性质的影响。
AI中文摘要：
过渡金属 kagome 磁体为研究层堆垛、磁有序与能带拓扑之间的相互作用提供了丰富平台。本文报道了通过分子束外延法制备高质量 kagome 金属 Co$_3$Sn 薄膜并对其开展实验研究的结果，该材料尚未合成出块体形式。结构与化学分析证实其为六方晶格结构（$P6_3/mmc$），由直接 A-B 堆垛的 Co$_3$Sn kagome 双层构成。磁强计测量显示其具有强面内易轴铁磁性，居里温度超过 300 K。磁输运测量表明其呈现金属行为，载流子密度 $n\boldsymbol{\u22485.01\times10^{22}\text{cm}^{-3}}$，且从 2 K 到室温范围内，反常霍尔电导率 $\boldsymbol{\u03c3_{\rm AHE}\boldsymbol{\u224890\boldsymbol{\u03a9}^{-1}\boldsymbol{\u00b7\text{cm}}^{-1}}$ 与温度无关。第一性原理密度泛函理论计算结果将该反常霍尔响应归因于自旋劈裂能带结构中费米能级附近的本征贝里曲率热点。研究结果确立 Co$_3$Sn 为室温 kagome 铁磁体，并强调了层堆垛顺序对 CoSn 家族 kagome 金属材料性质的影响。
英文摘要：
Transition-metal kagome magnets provide a rich platform for investigating the interplay between layer stacking, magnetic order, and band topology. Here, we report the molecular beam epitaxy and experimental investigation of high-quality thin films of the kagome metal Co$_3$Sn, which has not been synthesized in bulk form yet. Structural and chemical analyses confirm a hexagonal lattice structure ($P6_3/mmc$) composed of direct A-B stacked Co$_3$Sn kagome bilayers. Magnetometry reveals robust easy-plane ferromagnetism with a Curie temperature exceeding $300\,\text{K}$. Magneto-transport measurements demonstrate metallic behavior (carrier density $n\approx5.01\times10^{22}\,\text{cm}^{-3}$) alongside a temperature-independent anomalous Hall conductivity of $σ_{\rm AHE}\approx90\,Ω^{-1}\cdot{\rm cm}^{-1}$, extending from $2\,\text{K}$ up to room temperature. Results from first-principles density functional theory calculations attribute this anomalous Hall response to intrinsic Berry curvature hotspots near the Fermi level in the spin-split band structure. Our results establish Co$_3$Sn as a room-temperature kagome ferromagnet and highlight the impact of the layer stacking sequence on the material properties of kagome metals from the CoSn family.
