Chiral Dirac Fermion in a Collinear Antiferromagnet

Ao Zhang; Ke Deng; Jieming Sheng; Pengfei Liu; Shiv Kumar; Kenya Shimada; Zhicheng Jiang; Zhengtai Liu; Dawei Shen; Jiayu Li; Jun Ren; Le Wang; Liang Zhou; Yoshihisa Ishikawa; Takashi Ohhara; Qiang Zhang; Garry McIntyre; Dehong Yu; Enke Liu; Liusuo Wu; Chaoyu Chen; Qihang Liu

doi:10.1088/0256-307X/40/12/126101

Chiral Dirac Fermion in a Collinear Antiferromagnet

Ao Zhang, Ke Deng, Jieming Sheng, Pengfei Liu, Shiv Kumar, Kenya Shimada, Zhicheng Jiang, Zhengtai Liu, Dawei Shen, Jiayu Li, Jun Ren, Le Wang, Liang Zhou, Yoshihisa Ishikawa, Takashi Ohhara, Qiang Zhang, Garry McIntyre, Dehong Yu, Enke Liu, Liusuo WuChaoyu Chen, Qihang Liu

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Abstract

In a Dirac semimetal, the massless Dirac fermion has zero chirality, leading to surface states connected adiabatically to a topologically trivial surface state as well as vanishing anomalous Hall effect. Recently, it is predicted that in the nonrelativistic limit of certain collinear antiferromagnets, there exists a type of chiral “Dirac-like” fermion, whose dispersion manifests four-fold degenerate crossing points formed by spin-degenerate linear bands, with topologically protected Fermi arcs. Such an unconventional chiral fermion, protected by a hidden SU(2) symmetry in the hierarchy of an enhanced crystallographic group, namely spin space group, is not experimentally verified yet. Here, by angle-resolved photoemission spectroscopy measurements, we reveal the surface origin of the electron pocket at the Fermi surface in collinear antiferromagnet CoNb3S6. Combining with neutron diffraction and first-principles calculations, we suggest a multidomain collinear antiferromagnetic configuration, rendering the the existence of the Fermi-arc surface states induced by chiral Dirac-like fermions. Our work provides spectral evidence of the chiral Dirac-like fermion caused by particular spin symmetry in CoNb3S6, paving an avenue for exploring new emergent phenomena in antiferromagnets with unconventional quasiparticle excitations.

Original language	English
Article number	126101
Journal	Chinese Physics Letters
Volume	40
Issue number	12
DOIs	https://doi.org/10.1088/0256-307X/40/12/126101
State	Published - Dec 1 2023

Funding

We thank Professor Jia-Xin Yin for helpful discussions. This work was supported by the National Key R&D Program of China (Grant Nos. 2020YFA0308900 and 2022YFA1403700), the National Natural Science Foundation of China (Grant Nos. 12074163, 12134020, 11974157, 12104255, 12004159, and 12374146), Guangdong Provincial Key Laboratory for Computational Science and Material Design (Grant No. 2019B030301001), the Science, Technology and Innovation Commission of Shenzhen Municipality (Grant Nos. ZDSYS20190902092905285 and KQTD20190929173815000), Guangdong Basic and Applied Basic Research Foundation (Grant Nos. 2022B1515020046, 2021B1515130007, 2022A1515011915, 2019A1515110712, and 2022B1515130005), Shenzhen Science and Technology Program (Grant Nos. RCJC20221008092722009 and RCBS20210706092218039), the Guangdong Innovative and Entrepreneurial Research Team Program (Grant No. 2019ZT08C044), Center for Computational Science and Engineering and Core Research Facilities of Southern University of Science and Technology. The authors would also like to acknowledge the beam time awarded by Australia’s Nuclear Science and Technology Organisation (ANSTO) (Grant No. P8130). The neutron experiment at the Materials and Life Science Experimental Facility of the Japan Proton Accelerator Research Complex (J-PARC) was performed under a user program (Proposal No. 2019B0140). The ARPES measurement was performed at the Hiroshima Synchrotron Radiation Center (HiSOR) of Japan (Grant Nos. 22BG023 and 22BG029), and Shanghai Synchrotron Radiation Facility (SSRF) BL03U (Grant No. 2022-SSRF-PT-020848). The authors acknowledge the assistance of SUSTech Core Research Facilities.

Funders	Funder number
Shanghai Synchrotron Radiation Facility	2022-SSRF-PT-020848
Guangdong Innovative and Entrepreneurial Research Team Program	2019ZT08C044
National Natural Science Foundation of China	11974157, 12374146, 12004159, 12104255, 12134020, 12074163
Science, Technology and Innovation Commission of Shenzhen Municipality	ZDSYS20190902092905285, RCBS20210706092218039, KQTD20190929173815000, RCJC20221008092722009
National Key Research and Development Program of China	2020YFA0308900, 2022YFA1403700
Southern University of Science and Technology	22BG023, P8130, 22BG029
Guangdong Provincial Key Laboratory Of Computational Science And Material Design	2019B030301001
Basic and Applied Basic Research Foundation of Guangdong Province	2019A1515110712, 2022A1515011915, 2022B1515130005, 2021B1515130007, 2022B1515020046

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title = "Chiral Dirac Fermion in a Collinear Antiferromagnet",

abstract = "In a Dirac semimetal, the massless Dirac fermion has zero chirality, leading to surface states connected adiabatically to a topologically trivial surface state as well as vanishing anomalous Hall effect. Recently, it is predicted that in the nonrelativistic limit of certain collinear antiferromagnets, there exists a type of chiral “Dirac-like” fermion, whose dispersion manifests four-fold degenerate crossing points formed by spin-degenerate linear bands, with topologically protected Fermi arcs. Such an unconventional chiral fermion, protected by a hidden SU(2) symmetry in the hierarchy of an enhanced crystallographic group, namely spin space group, is not experimentally verified yet. Here, by angle-resolved photoemission spectroscopy measurements, we reveal the surface origin of the electron pocket at the Fermi surface in collinear antiferromagnet CoNb3S6. Combining with neutron diffraction and first-principles calculations, we suggest a multidomain collinear antiferromagnetic configuration, rendering the the existence of the Fermi-arc surface states induced by chiral Dirac-like fermions. Our work provides spectral evidence of the chiral Dirac-like fermion caused by particular spin symmetry in CoNb3S6, paving an avenue for exploring new emergent phenomena in antiferromagnets with unconventional quasiparticle excitations.",

author = "Ao Zhang and Ke Deng and Jieming Sheng and Pengfei Liu and Shiv Kumar and Kenya Shimada and Zhicheng Jiang and Zhengtai Liu and Dawei Shen and Jiayu Li and Jun Ren and Le Wang and Liang Zhou and Yoshihisa Ishikawa and Takashi Ohhara and Qiang Zhang and Garry McIntyre and Dehong Yu and Enke Liu and Liusuo Wu and Chaoyu Chen and Qihang Liu",

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AU - Zhang, Ao

AU - Deng, Ke

AU - Sheng, Jieming

AU - Liu, Pengfei

AU - Kumar, Shiv

AU - Shimada, Kenya

AU - Jiang, Zhicheng

AU - Liu, Zhengtai

AU - Shen, Dawei

AU - Li, Jiayu

AU - Ren, Jun

AU - Wang, Le

AU - Zhou, Liang

AU - Ishikawa, Yoshihisa

AU - Ohhara, Takashi

AU - Zhang, Qiang

AU - McIntyre, Garry

AU - Yu, Dehong

AU - Liu, Enke

AU - Wu, Liusuo

AU - Chen, Chaoyu

AU - Liu, Qihang

PY - 2023/12/1

Y1 - 2023/12/1

N2 - In a Dirac semimetal, the massless Dirac fermion has zero chirality, leading to surface states connected adiabatically to a topologically trivial surface state as well as vanishing anomalous Hall effect. Recently, it is predicted that in the nonrelativistic limit of certain collinear antiferromagnets, there exists a type of chiral “Dirac-like” fermion, whose dispersion manifests four-fold degenerate crossing points formed by spin-degenerate linear bands, with topologically protected Fermi arcs. Such an unconventional chiral fermion, protected by a hidden SU(2) symmetry in the hierarchy of an enhanced crystallographic group, namely spin space group, is not experimentally verified yet. Here, by angle-resolved photoemission spectroscopy measurements, we reveal the surface origin of the electron pocket at the Fermi surface in collinear antiferromagnet CoNb3S6. Combining with neutron diffraction and first-principles calculations, we suggest a multidomain collinear antiferromagnetic configuration, rendering the the existence of the Fermi-arc surface states induced by chiral Dirac-like fermions. Our work provides spectral evidence of the chiral Dirac-like fermion caused by particular spin symmetry in CoNb3S6, paving an avenue for exploring new emergent phenomena in antiferromagnets with unconventional quasiparticle excitations.

AB - In a Dirac semimetal, the massless Dirac fermion has zero chirality, leading to surface states connected adiabatically to a topologically trivial surface state as well as vanishing anomalous Hall effect. Recently, it is predicted that in the nonrelativistic limit of certain collinear antiferromagnets, there exists a type of chiral “Dirac-like” fermion, whose dispersion manifests four-fold degenerate crossing points formed by spin-degenerate linear bands, with topologically protected Fermi arcs. Such an unconventional chiral fermion, protected by a hidden SU(2) symmetry in the hierarchy of an enhanced crystallographic group, namely spin space group, is not experimentally verified yet. Here, by angle-resolved photoemission spectroscopy measurements, we reveal the surface origin of the electron pocket at the Fermi surface in collinear antiferromagnet CoNb3S6. Combining with neutron diffraction and first-principles calculations, we suggest a multidomain collinear antiferromagnetic configuration, rendering the the existence of the Fermi-arc surface states induced by chiral Dirac-like fermions. Our work provides spectral evidence of the chiral Dirac-like fermion caused by particular spin symmetry in CoNb3S6, paving an avenue for exploring new emergent phenomena in antiferromagnets with unconventional quasiparticle excitations.

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Chiral Dirac Fermion in a Collinear Antiferromagnet

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