论文标题

Co $ _3 $ sn $ _2 $ S $ _2 $的拓扑Weyl Loop的签名

Signatures of a topological Weyl loop in Co$_3$Sn$_2$S$_2$

论文作者

Belopolski, Ilya, Cochran, Tyler A., Tsirkin, Stepan S., Guguchia, Zurab, Yin, Jiaxin, Zhang, Songtian S., Cheng, Zijia, Liu, Xiaoxiong, Chang, Guoqing, Yang, Xian, Multer, Daniel, Kim, Timur K., Cacho, Cephise, Felser, Claudia, Neupert, Titus, Hasan, M. Zahid

论文摘要

量子磁铁中物质的新拓扑阶段的搜索已成为凝结物理学的前沿。在这里,我们使用最先进的角度分辨光发射光谱(ARPES)来研究其铁磁阶段的CO $ _3 $ sn $ _2 $ _2 $ s $ _2 $的单晶。我们首次报告拓扑Weyl环的签名。从基本的对称考虑因素来看,如果旋转轨道耦合(SOC)严格为零,但可能会在有限的SOC下与可能的Weyl点相处,则该磁性Weyl环将是无间隙的。我们指出,迄今为止,高分辨率ARPES的结果无法明确解决沿Weyl环路的任何地方的SOC间隙,从而打开了CO $ _3 $ SN $ _2 $ _2 $ _2 $ S $ _2 $ host零weyl点或一些非零点Weyl点的可能性。在我们的样品表面上,我们进一步观察了可能的费米弧,但我们无法使用已建立的计数标准清楚地验证其拓扑性质。结果,我们认为,从光发射光谱的角度来看,co $ _3 $ sn $ _2 $ _2 $ s $ _2 $的Weyl点和费米弧的存在仍然模棱两可。我们的结果对正在进行的CO $ _3 $ SN $ _2 $ S $ _2 $和其他拓扑磁铁的调查具有影响。

The search for novel topological phases of matter in quantum magnets has emerged as a frontier of condensed matter physics. Here we use state-of-the-art angle-resolved photoemission spectroscopy (ARPES) to investigate single crystals of Co$_3$Sn$_2$S$_2$ in its ferromagnetic phase. We report for the first time signatures of a topological Weyl loop. From fundamental symmetry considerations, this magnetic Weyl loop is expected to be gapless if spin-orbit coupling (SOC) is strictly zero but gapped, with possible Weyl points, under finite SOC. We point out that high-resolution ARPES results to date cannot unambiguously resolve the SOC gap anywhere along the Weyl loop, leaving open the possibility that Co$_3$Sn$_2$S$_2$ hosts zero Weyl points or some non-zero number of Weyl points. On the surface of our samples, we further observe a possible Fermi arc, but we are unable to clearly verify its topological nature using the established counting criteria. As a result, we argue that from the point of view of photoemission spectroscopy the presence of Weyl points and Fermi arcs in Co$_3$Sn$_2$S$_2$ remains ambiguous. Our results have implications for ongoing investigations of Co$_3$Sn$_2$S$_2$ and other topological magnets.

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