Signatures of a topological Weyl loop in magnetic semimetal Co3Sn2S2*

The search for novel topological phases of matter in quantum magnets has emerged as a frontier of condensed matter physics. Here we present our high-resolution angle-resolved photoemission spectroscopy results on single crystals of Co3Sn2S2 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 the 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. As a result, we argue that from the point of view of photoemission spectroscopy the presence of Weyl points in Co3Sn2S2 remains ambiguous. We will also present our recent results on the tunability of the electronic structure in magnetic semimetal Co3Sn2S2.

[1] Belopolski Ilya et al. Signatures of a topological Weyl loop in Co3Sn2S2. arXiv preprint arXiv:2005.02400, (2020).

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