Weyl fermion excitations in the ideal Weyl semimetal CuTlSe2

Wang, C. N.; Tay, D.; Dong, Q. X.; Okvátovity, Z.; Huddart, B. M.; Ma, C. Y.; Yokoyama, K.; Yu, L.; Lancaster, T.; Chen, G. F.; Ott, H.-R.; Shiroka, T.

Abstract

An ideal Weyl semimetal is characterized by a dispersion in which only Weyl cones intersect the Fermi level, with low-energy behavior being governed by Weyl fermions. Although ideal Weyl semimetals have long been anticipated, only a few are realized in nonmagnetic materials. In this study, we confirm the presence of Weyl-fermion excitations in the ideal Weyl semimetal CuTlSe2 via a combination of magnetoresistance, Hall-effect, magnetic-susceptibility, nuclear magnetic resonance (NMR), and muon-spin relaxation (µSR) experiments. Magnetoresistance measurements reveal a negative longitudinal magnetoresistance (LMR), which scales as B2, while Hall-effect results indicate a predominant contribution from Weyl fermions with a hole-type charge. Magnetic susceptibility and µSR measurements indicate the lack of any intrinsic spontaneous magnetic moments down to base temperature. Finally, the NMR results can be modeled by a two-component effective Hamiltonian, which reproduces well the temperature-dependent Cu63 NMR (T1T)−1 factor, shown to scale as T2 below 100 K and as T1 above 100 K. Overall, we find that the extremely low concentration (1017cm−3) of carriers in CuTlSe2 originates from an ideal nonmagnetic Weyl semimetallic state, persisting up to a thermal excitation energy of 9 meV (100 K), above which trivial electronic bands close to EF take over. Our findings highlight CuTlSe2 as a new member of the intriguing class of Weyl semimetals. Published by the American Physical Society 2024

Citation

Wang, C. N., Tay, D., Dong, Q. X., Okvátovity, Z., Huddart, B. M., Ma, C. Y., Yokoyama, K., Yu, L., Lancaster, T., Chen, G. F., Ott, H.-R., & Shiroka, T. (2024). Weyl fermion excitations in the ideal Weyl semimetal CuTlSe2. Physical Review Research, 6(3), Article 033229. https://doi.org/10.1103/physrevresearch.6.033229

• Journal Article Type: Article
• Acceptance Date: Aug 7, 2024
• Online Publication Date: Sep 3, 2024
• Publication Date: 2024-09
• Deposit Date: Sep 4, 2024
• Publicly Available Date: Sep 6, 2024
• Journal: Physical Review Research
• Electronic ISSN: 2643-1564
• Publisher: American Physical Society
• Peer Reviewed: Peer Reviewed
• Volume: 6
• Issue: 3
• Article Number: 033229
• DOI: https://doi.org/10.1103/physrevresearch.6.033229
• Public URL: https://durham-repository.worktribe.com/output/2786005