Localized spin-orbit polaron in magnetic Weyl semimetal Co3Sn2S2

Yuqing Xing,Wenhong Wang,Shixuan Du,Qi Zheng,Hui Chen,Baogen Shen,Geng Li,Ruisong Ma,Yuyang Zhang ,Haitao Yang,Qiangwei Yin,Yuxiang Gao,Wei Ji,Jianlei Shen,Li Huang,Guojian Qian,Qi Wang,Enke Liu,Chengmin Shen,Bin Hu,Xiao Lin,Lu Cao,Peng Fan,Hechang Lei,Xianli Zhang,Ziqiang Wang,Hongjun Gao

doi:10.1038/s41467-020-19440-2

Abstract

The kagome lattice Co3Sn2S2 exhibits the quintessential topological phenomena of a magnetic Weyl semimetal such as the chiral anomaly and Fermi-arc surface states. Probing its magnetic properties is crucial for understanding this correlated topological state. Here, using spin-polarized scanning tunneling microscopy/spectroscopy (STM/S) and non-contact atomic force microscopy (nc-AFM) combined with first-principle calculations, we report the discovery of localized spin-orbit polarons (SOPs) with three-fold rotation symmetry nucleated around single S-vacancies in Co3Sn2S2. The SOPs carry a magnetic moment and a large diamagnetic orbital magnetization of a possible topological origin associated relating to the diamagnetic circulating current around the S-vacancy. Appreciable magneto-elastic coupling of the SOP is detected by nc-AFM and STM. Our findings suggest that the SOPs can enhance magnetism and more robust time-reversal-symmetry-breaking topological phenomena. Controlled engineering of the SOPs may pave the way toward practical applications in functional quantum devices.

Highlights

The kagome lattice Co3Sn2S2 exhibits the quintessential topological phenomena of a magnetic Weyl semimetal such as the chiral anomaly and Fermi-arc surface states
We term this new excitation as a localized spin-orbit polaron (SOP) and argue that the large orbital magnetization has a topological origin associated with the Berry phase and the persistent circulating current due to the magnetoelectric effect of the topological magnet
In order to further identify the two surfaces, we conducted the local contact potential difference (LCPD) measurement on both surfaces using the low-temperature (4.5 K) non-contact atomic force microscopy (nc-AFM)/scanning tunneling microscopy (STM), which is based on a qPlus sensor[31]

Summary

Introduction

The kagome lattice Co3Sn2S2 exhibits the quintessential topological phenomena of a magnetic Weyl semimetal such as the chiral anomaly and Fermi-arc surface states. Co3Sn2S2 has been discovered to exhibit novel phenomena such as surface-termination-dependent topological Fermi arcs[13] and disorder-induced elevation of intrinsic anomalous Hall conductance[18], making it an ideal platform to study the defect excitations and its correlation to the topological properties of the Weyl semimetal. Our main finding is the localized magnetic polarons nucleated around single atomic S vacancies on S-terminated surface in Co3Sn2S2 by spin-polarized STM They emerge as bound states in the conductance map with a three-fold rotation symmetry. Appreciable magneto-elastic coupling is detected near the Svacancy We term this new excitation as a localized spin-orbit polaron (SOP) and argue that the large orbital magnetization has a topological origin associated with the Berry phase and the persistent circulating current due to the magnetoelectric effect of the topological magnet

Methods

Results

Conclusion