Journal article
Optical signatures of multifold fermions in the chiral topological semimetal CoSi
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, v 117(44), pp 27104-27110
03 Nov 2020
PMID: 33077590
Abstract
We report the optical conductivity in high-quality crystals of the chiral topological semimetal CoSi, which hosts exotic quasiparticles known as multifold fermions. We find that the optical response is separated into several distinct regions as a function of frequency, each dominated by different types of quasiparticles. The low-frequency intraband response is captured by a narrow Drude peak from a high-mobility electron pocket of double Weyl quasiparticles, and the temperature dependence of the spectral weight is consistent with its Fermi velocity. By subtracting the low-frequency sharp Drude and phonon peaks at low temperatures, we reveal two intermediate quasilinear interband contributions separated by a kink at 0.2 eV. Using Wannier tight-binding models based on first-principle calculations, we link the optical conductivity above and below 0.2 eV to interband transitions near the double Weyl fermion and a threefold fermion, respectively. We analyze and determine the chemical potential relative to the energy of the threefold fermion, revealing the importance of transitions between a linearly dispersing band and a flat band. More strikingly, below 0.1 eV our data are best explained if spin-orbit coupling is included, suggesting that at these energies, the optical response is governed by transitions between a previously unobserved fourfold spin-3/2 node and a Weyl node. Our comprehensive combined experimental and theoretical study provides a way to resolve different types of multifold fermions in CoSi at different energy. More broadly, our results provide the necessary basis to interpret the burgeoning set of optical and transport experiments in chiral topological semimetals.
Metrics
Details
- Title
- Optical signatures of multifold fermions in the chiral topological semimetal CoSi
- Creators
- Bing Xu - University of FribourgZhenyao Fang - University of PennsylvaniaMiguel-Ángel Sánchez-Martínez - Université Grenoble AlpesJorn W. F. VenderbosZhuoliang Ni - University of PennsylvaniaTian Qiu - University of PennsylvaniaKaustuv Manna - Max Planck Institut fur Chemische Physik fester Stoffe, 01187 Dresden, Germany,] (ORCID:0000000294422321Kefeng Wang - University of Maryland, College ParkJohnpierre PaglioneChristian Bernhard - University of FribourgClaudia FelserEugene J. Mele - University of PennsylvaniaAdolfo G. Grushin - Université Grenoble AlpesAndrew M. Rappe - Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323,] (ORCID:0000000346206496Liang Wu - Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104,] (ORCID:0000000316967809
- Publication Details
- PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, v 117(44), pp 27104-27110
- Publisher
- NATL ACAD SCIENCES; WASHINGTON
- Grant note
- We thank F. de Juan, C. L. Kane, and Y. Zhang for helpful discussion. Z.N. and L.W. are supported by Army Research Office Grant W911NF1910342. B.X. and C.B. are supported by Schweizerische Nationalfonds Grant 200020-172611. Z.F., J.W.F.V., and E.J.M. are supported by the US National Science Foundation under grant DMR-1720530 (Materials Research Science and Engineering Center program). M.-A.S.-M. acknowledges support from the European Union's Horizon 2020 Research and Innovation Programme under Marie Sklodowska-Curie Grant 754303 and the GreQuE Cofund Programme. K.M. and C.F. acknowledge financial support from European Research Council Advanced Grant 742068 TOP-MAT and Deutsche Forschungsgemeinschaft Projects 258499086 and FE 63330-1. K.W. and J.P. are supported by the Gordon and Betty Moore Foundation's EPiQS Initiative Grant GBMF9071 and the Maryland Quantum Materials Center. A.G.G. is supported by ANR Grant ANR-18-CE30-0001-01 (TOPODRIVE) and the European Union's Horizon 2020 Research and Innovation Programme Grant 829044 (SCHINES). A.M.R. was supported by Department of Energy, Office of Basic Energy Sciences Grant DE-FG02-07ER46431. Computational support was provided by the National Energy Research Scientific Computing Center.
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Physics; Drexel University
- Web of Science ID
- WOS:000587503000013
- Scopus ID
- 2-s2.0-85095665642
- Other Identifier
- 991021860679404721
InCites Highlights
Data related to this publication, from InCites Benchmarking & Analytics tool:
- Collaboration types
- Domestic collaboration
- International collaboration
- Web of Science research areas
- Physics, Multidisciplinary