Spin fluctuation induced Weyl semimetal state in the paramagnetic phase of EuCd2As2

J. Z. Ma; S. M. Nie; C. J. Yi; J. Jandke; T. Shang; M. Y. Yao; M. Naamneh; L. Q. Yan; Y. Sun; A. Chikina; V. N. Strocov; M. Medarde; M. Song; Y. M. Xiong; G. Xu; W. Wulfhekel; J. Mesot; M. Reticcioli; C. Franchini; C. Mudry; M. Müller; Y. G. Shi; T. Qian; H. Ding; M. Shi

doi:10.1126/sciadv.aaw4718

Spin fluctuation induced Weyl semimetal state in the paramagnetic phase of EuCd₂As₂

J. Z. Ma, S. M. Nie, C. J. Yi, J. Jandke, T. Shang, M. Y. Yao, M. Naamneh, L. Q. Yan, Y. Sun, A. Chikina, V. N. Strocov, M. Medarde, M. Song, Y. M. Xiong, G. Xu, W. Wulfhekel, J. Mesot, M. Reticcioli, C. Franchini, C. MudryM. Müller, Y. G. Shi, T. Qian, H. Ding, M. Shi

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Abstract

Weyl fermions as emergent quasiparticles can arise in Weyl semimetals (WSMs) in which the energy bands are nondegenerate, resulting from inversion or time-reversal symmetry breaking. Nevertheless, experimental evidence for magnetically induced WSMs is scarce. Here, using photoemission spectroscopy, we observe that the degeneracy of Bloch bands is already lifted in the paramagnetic phase of EuCd₂As₂. We attribute this effect to the itinerant electrons experiencing quasi-static and quasi–long-range ferromagnetic fluctuations. Moreover, the spin-nondegenerate band structure harbors a pair of ideal Weyl nodes near the Fermi level. Hence, we show that long-range magnetic order and the spontaneous breaking of time-reversal symmetry are not essential requirements for WSM states in centrosymmetric systems and that WSM states can emerge in a wider range of condensed matter systems than previously thought.

Original language	English
Article number	eaaw4718
Journal	Science advances
Volume	5
Issue number	7
DOIs	https://doi.org/10.1126/sciadv.aaw4718
State	Published - 12 Jul 2019
Externally published	Yes

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Ma, J. Z., Nie, S. M., Yi, C. J., Jandke, J., Shang, T., Yao, M. Y., Naamneh, M., Yan, L. Q., Sun, Y., Chikina, A., Strocov, V. N., Medarde, M., Song, M., Xiong, Y. M., Xu, G., Wulfhekel, W., Mesot, J., Reticcioli, M., Franchini, C., ... Shi, M. (2019). Spin fluctuation induced Weyl semimetal state in the paramagnetic phase of EuCd₂As₂ Science advances, 5(7), Article eaaw4718. https://doi.org/10.1126/sciadv.aaw4718

@article{c11f03c16cd64792a2e518f4735c3b3a,

title = "Spin fluctuation induced Weyl semimetal state in the paramagnetic phase of EuCd2As2 ",

abstract = "Weyl fermions as emergent quasiparticles can arise in Weyl semimetals (WSMs) in which the energy bands are nondegenerate, resulting from inversion or time-reversal symmetry breaking. Nevertheless, experimental evidence for magnetically induced WSMs is scarce. Here, using photoemission spectroscopy, we observe that the degeneracy of Bloch bands is already lifted in the paramagnetic phase of EuCd2As2. We attribute this effect to the itinerant electrons experiencing quasi-static and quasi–long-range ferromagnetic fluctuations. Moreover, the spin-nondegenerate band structure harbors a pair of ideal Weyl nodes near the Fermi level. Hence, we show that long-range magnetic order and the spontaneous breaking of time-reversal symmetry are not essential requirements for WSM states in centrosymmetric systems and that WSM states can emerge in a wider range of condensed matter systems than previously thought.",

author = "Ma, {J. Z.} and Nie, {S. M.} and Yi, {C. J.} and J. Jandke and T. Shang and Yao, {M. Y.} and M. Naamneh and Yan, {L. Q.} and Y. Sun and A. Chikina and Strocov, {V. N.} and M. Medarde and M. Song and Xiong, {Y. M.} and G. Xu and W. Wulfhekel and J. Mesot and M. Reticcioli and C. Franchini and C. Mudry and M. M{\"u}ller and Shi, {Y. G.} and T. Qian and H. Ding and M. Shi",

note = "Funding Information: We acknowledge E. Rienks, H. Luetkens, L.-Y. Kong, Y.-G. Zhong, H.-J. Liu, S.-Y Gao, X.-L Peng, and Y.-B. Huang for the assistance during the measurements. We acknowledge Y. Goryunov, H.-M. Weng, L. Korosec, R. H. Ott, P. Hautle, Q. S. Wu, V. M. Katukuri, and O. Yazyev for useful discussions. C.M. and M.M{\"u}. thank B. Roessli for useful discussions. We acknowledge S. Blundell for sharing the mSR beamtime. Funding: This work was supported by the NCCR-MARVEL funded by the Swiss National Science Foundation, the Sino-Swiss Science and Technology Cooperation (grant no. IZLCZ2-170075), the Ministry of Science and Technology of China (grant nos. 2016YFA0300600, 2016YFA0401000, 2017YFA0302901, and 2016YFA0300404), the National Natural Science Foundation of China (grant nos. 11622435, 11474340, 11474330, 11674369, and U1832202), the Chinese Academy of Sciences (grant nos. QYZDB-SSW-SLH043, XDB07000000, XDPB08-1, and XDB28000000), and Beijing Municipal Science & Technology Commission (grant nos. Z171100002017018 and Z181100004218005). This project has received funding from the European Union{\textquoteright}s Horizon 2020 research and innovation programme under the Marie Sk{\l}odowska-Curie grant Publisher Copyright: Copyright {\textcopyright} 2019 The Authors, some rights reserved;",

year = "2019",

month = jul,

day = "12",

doi = "10.1126/sciadv.aaw4718",

language = "English",

volume = "5",

journal = "Science advances",

issn = "2375-2548",

publisher = "American Association for the Advancement of Science",

number = "7",

}

Ma, JZ, Nie, SM, Yi, CJ, Jandke, J, Shang, T, Yao, MY, Naamneh, M, Yan, LQ, Sun, Y, Chikina, A, Strocov, VN, Medarde, M, Song, M, Xiong, YM, Xu, G, Wulfhekel, W, Mesot, J, Reticcioli, M, Franchini, C, Mudry, C, Müller, M, Shi, YG, Qian, T, Ding, H & Shi, M 2019, 'Spin fluctuation induced Weyl semimetal state in the paramagnetic phase of EuCd₂As₂ ', Science advances, vol. 5, no. 7, eaaw4718. https://doi.org/10.1126/sciadv.aaw4718

TY - JOUR

T1 - Spin fluctuation induced Weyl semimetal state in the paramagnetic phase of EuCd2As2

AU - Ma, J. Z.

AU - Nie, S. M.

AU - Yi, C. J.

AU - Jandke, J.

AU - Shang, T.

AU - Yao, M. Y.

AU - Naamneh, M.

AU - Yan, L. Q.

AU - Sun, Y.

AU - Chikina, A.

AU - Strocov, V. N.

AU - Medarde, M.

AU - Song, M.

AU - Xiong, Y. M.

AU - Xu, G.

AU - Wulfhekel, W.

AU - Mesot, J.

AU - Reticcioli, M.

AU - Franchini, C.

AU - Mudry, C.

AU - Müller, M.

AU - Shi, Y. G.

AU - Qian, T.

AU - Ding, H.

AU - Shi, M.

N1 - Funding Information: We acknowledge E. Rienks, H. Luetkens, L.-Y. Kong, Y.-G. Zhong, H.-J. Liu, S.-Y Gao, X.-L Peng, and Y.-B. Huang for the assistance during the measurements. We acknowledge Y. Goryunov, H.-M. Weng, L. Korosec, R. H. Ott, P. Hautle, Q. S. Wu, V. M. Katukuri, and O. Yazyev for useful discussions. C.M. and M.Mü. thank B. Roessli for useful discussions. We acknowledge S. Blundell for sharing the mSR beamtime. Funding: This work was supported by the NCCR-MARVEL funded by the Swiss National Science Foundation, the Sino-Swiss Science and Technology Cooperation (grant no. IZLCZ2-170075), the Ministry of Science and Technology of China (grant nos. 2016YFA0300600, 2016YFA0401000, 2017YFA0302901, and 2016YFA0300404), the National Natural Science Foundation of China (grant nos. 11622435, 11474340, 11474330, 11674369, and U1832202), the Chinese Academy of Sciences (grant nos. QYZDB-SSW-SLH043, XDB07000000, XDPB08-1, and XDB28000000), and Beijing Municipal Science & Technology Commission (grant nos. Z171100002017018 and Z181100004218005). This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant Publisher Copyright: Copyright © 2019 The Authors, some rights reserved;

PY - 2019/7/12

Y1 - 2019/7/12

N2 - Weyl fermions as emergent quasiparticles can arise in Weyl semimetals (WSMs) in which the energy bands are nondegenerate, resulting from inversion or time-reversal symmetry breaking. Nevertheless, experimental evidence for magnetically induced WSMs is scarce. Here, using photoemission spectroscopy, we observe that the degeneracy of Bloch bands is already lifted in the paramagnetic phase of EuCd2As2. We attribute this effect to the itinerant electrons experiencing quasi-static and quasi–long-range ferromagnetic fluctuations. Moreover, the spin-nondegenerate band structure harbors a pair of ideal Weyl nodes near the Fermi level. Hence, we show that long-range magnetic order and the spontaneous breaking of time-reversal symmetry are not essential requirements for WSM states in centrosymmetric systems and that WSM states can emerge in a wider range of condensed matter systems than previously thought.

AB - Weyl fermions as emergent quasiparticles can arise in Weyl semimetals (WSMs) in which the energy bands are nondegenerate, resulting from inversion or time-reversal symmetry breaking. Nevertheless, experimental evidence for magnetically induced WSMs is scarce. Here, using photoemission spectroscopy, we observe that the degeneracy of Bloch bands is already lifted in the paramagnetic phase of EuCd2As2. We attribute this effect to the itinerant electrons experiencing quasi-static and quasi–long-range ferromagnetic fluctuations. Moreover, the spin-nondegenerate band structure harbors a pair of ideal Weyl nodes near the Fermi level. Hence, we show that long-range magnetic order and the spontaneous breaking of time-reversal symmetry are not essential requirements for WSM states in centrosymmetric systems and that WSM states can emerge in a wider range of condensed matter systems than previously thought.

UR - http://www.scopus.com/inward/record.url?scp=85069843430&partnerID=8YFLogxK

U2 - 10.1126/sciadv.aaw4718

DO - 10.1126/sciadv.aaw4718

M3 - Article

C2 - 31309151

AN - SCOPUS:85069843430

SN - 2375-2548

VL - 5

JO - Science advances

JF - Science advances

IS - 7

M1 - eaaw4718

ER -

Spin fluctuation induced Weyl semimetal state in the paramagnetic phase of EuCd₂As₂

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