Universität zu Köln

Takane, Daichi, Wang, Zhiwei ORCID: 0000-0003-0182-2471, Souma, Seigo, Nakayama, Kosuke, Nakamura, Takechika, Oinuma, Hikaru, Nakata, Yuki, Iwasawa, Hideaki ORCID: 0000-0001-6760-4085, Cacho, Cephise ORCID: 0000-0002-0058-5817, Kim, Timur ORCID: 0000-0003-4201-4462, Horiba, Koji ORCID: 0000-0002-1124-0451, Kumigashira, Hiroshi, Takahashi, Takashi, Ando, Yoichi ORCID: 0000-0002-3553-3355 and Sato, Takafumi ORCID: 0000-0002-4544-5463 (2019). Observation of Chiral Fermions with a Large Topological Charge and Associated Fermi-Arc Surface States in CoSi. Phys. Rev. Lett., 122 (7). COLLEGE PK: AMER PHYSICAL SOC. ISSN 1079-7114

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Abstract

Topological semimetals materialize a new state of quantum matter where massless fermions protected by a specific crystal symmetry host exotic quantum phenomena. Distinct from well-known Dirac and Weyl fermions, structurally chiral topological semimetals are predicted to host new types of massless fermions characterized by a large topological charge, whereas such exotic fermions are yet to be experimentally established. Here, by using angle-resolved photoemission spectroscopy, we experimentally demonstrate that a transition-metal silicide CoSi hosts two types of chiral topological fermions, a spin-1 chiral fermion and a double Weyl fermion, in the center and corner of the bulk Brillouin zone, respectively. Intriguingly, we found that the bulk Fermi surfaces are purely composed of the energy bands related to these fermions. We also find the surface states connecting the Fermi surfaces associated with these fermions, suggesting the existence of the predicted Fermi-arc surface states. Our result provides the first experimental evidence for the chiral topological fermions beyond Dirac and Weyl fermions in condensed-matter systems, and paves the pathway toward realizing exotic electronic properties associated with unconventional chiral fermions.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Takane, Daichi UNSPECIFIED UNSPECIFIED UNSPECIFIED Wang, Zhiwei UNSPECIFIED orcid.org/0000-0003-0182-2471 UNSPECIFIED Souma, Seigo UNSPECIFIED UNSPECIFIED UNSPECIFIED Nakayama, Kosuke UNSPECIFIED UNSPECIFIED UNSPECIFIED Nakamura, Takechika UNSPECIFIED UNSPECIFIED UNSPECIFIED Oinuma, Hikaru UNSPECIFIED UNSPECIFIED UNSPECIFIED Nakata, Yuki UNSPECIFIED UNSPECIFIED UNSPECIFIED Iwasawa, Hideaki UNSPECIFIED orcid.org/0000-0001-6760-4085 UNSPECIFIED Cacho, Cephise UNSPECIFIED orcid.org/0000-0002-0058-5817 UNSPECIFIED Kim, Timur UNSPECIFIED orcid.org/0000-0003-4201-4462 UNSPECIFIED Horiba, Koji UNSPECIFIED orcid.org/0000-0002-1124-0451 UNSPECIFIED Kumigashira, Hiroshi UNSPECIFIED UNSPECIFIED UNSPECIFIED Takahashi, Takashi UNSPECIFIED UNSPECIFIED UNSPECIFIED Ando, Yoichi UNSPECIFIED orcid.org/0000-0002-3553-3355 UNSPECIFIED Sato, Takafumi UNSPECIFIED orcid.org/0000-0002-4544-5463 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-156447
DOI:	10.1103/PhysRevLett.122.076402
Journal or Publication Title:	Phys. Rev. Lett.
Volume:	122
Number:	7
Date:	2019
Publisher:	AMER PHYSICAL SOC
Place of Publication:	COLLEGE PK
ISSN:	1079-7114
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Physics > Institute of Physics II
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language MAJORANA FERMIONS; SEMIMETAL; SUPERCONDUCTOR; DISCOVERY Multiple languages Physics, Multidisciplinary Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/15644