Electronic correlations and flattened band in magnetic Weyl semimetal candidate Co3Sn2S2

Yueshan Xu; Jianzhou Zhao; Changjiang Yi; Qi Wang; Qiangwei Yin; Yilin Wang; Xiaolei Hu; Luyang Wang; Enke Liu; Gang Xu; Ling Lu; Alexey A Soluyanov; Hechang Lei; Youguo Shi; Jianlin Luo; Zhi-Guo Chen

doi:10.1038/s41467-020-17234-0

Electronic correlations and flattened band in magnetic Weyl semimetal candidate Co₃Sn₂S₂

Nat Commun. 2020 Aug 10;11(1):3985. doi: 10.1038/s41467-020-17234-0.

Authors

Yueshan Xu^#^{1

2}, Jianzhou Zhao^#^{3

4}, Changjiang Yi^#^{1

2}, Qi Wang⁵, Qiangwei Yin⁵, Yilin Wang⁶, Xiaolei Hu^{1

2}, Luyang Wang⁷, Enke Liu^{1

8}, Gang Xu⁹, Ling Lu^{1

8}, Alexey A Soluyanov⁴, Hechang Lei⁵, Youguo Shi^{1

8}, Jianlin Luo^{1

8}, Zhi-Guo Chen^{10

11}

Affiliations

¹ Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, 100190, Beijing, China.
² School of Physical Sciences, University of Chinese Academy of Sciences, 100190, Beijing, China.
³ Co-Innovation Center for New Energetic Materials, Southwest University of Science and Technology, Mianyang, 621010, Sichuan, China.
⁴ Physik-Institut, Universität Zürich, Winterthurerstrasse 190, Zurich, CH-8057, Switzerland.
⁵ Department of Physics, Beijing Key Laboratory of Opto-electronic Functional Materials and Micro-nano Devices, Renmin University of China, 100872, Beijing, China.
⁶ Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory, Upton, New York, 11973, USA.
⁷ State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics, Sun Yat-Sen University, 510275, Guangzhou, China.
⁸ Songshan Lake Materials Laboratory, Dongguan, 523808, Guangdong, China.
⁹ Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, 430074, Hubei, China.
¹⁰ Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, 100190, Beijing, China. zgchen@iphy.ac.cn.
¹¹ Songshan Lake Materials Laboratory, Dongguan, 523808, Guangdong, China. zgchen@iphy.ac.cn.

^# Contributed equally.

Abstract

The interplay between electronic correlations and topological protection may offer a rich avenue for discovering emergent quantum phenomena in condensed matter. However, electronic correlations have so far been little investigated in Weyl semimetals (WSMs) by experiments. Here, we report a combined optical spectroscopy and theoretical calculation study on the strength and effect of electronic correlations in a magnet Co₃Sn₂S₂. The electronic kinetic energy estimated from our optical data is about half of that obtained from single-particle ab initio calculations in the ferromagnetic ground state, which indicates intermediate-strength electronic correlations in this system. Furthermore, comparing the energy and side-slope ratios between the interband-transition peaks at high energies in the experimental and single-particle-calculation-derived optical conductivity spectra with the bandwidth-renormalization factors obtained by many-body calculations enables us to estimate the Coulomb-interaction strength (U ∼ 4 eV) in Co₃Sn₂S₂. Besides, a sharp experimental optical conductivity peak at low energy, which is absent in the single-particle-calculation-derived spectrum but is consistent with the optical conductivity peaks obtained by many-body calculations with U ∼ 4 eV, indicates that an electronic band connecting the two Weyl cones is flattened by electronic correlations and emerges near the Fermi energy in Co₃Sn₂S₂. Our work paves the way for exploring flat-band-generated quantum phenomena in WSMs.