Atomically Sharp Internal Interface in a Chiral Weyl Semimetal Nanowire

Nitish Mathur; Fang Yuan; Guangming Cheng; Sahal Kaushik; Iñigo Robredo; Maia G Vergniory; Jennifer Cano; Nan Yao; Song Jin; Leslie M Schoop

doi:10.1021/acs.nanolett.2c05100

Atomically Sharp Internal Interface in a Chiral Weyl Semimetal Nanowire

Nano Lett. 2023 Apr 12;23(7):2695-2702. doi: 10.1021/acs.nanolett.2c05100. Epub 2023 Mar 15.

Authors

Nitish Mathur^{1

2}, Fang Yuan¹, Guangming Cheng³, Sahal Kaushik⁴, Iñigo Robredo^{5

6}, Maia G Vergniory^{5

6}, Jennifer Cano^{7

8}, Nan Yao³, Song Jin², Leslie M Schoop¹

Affiliations

¹ Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States.
² Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States.
³ Princeton Institute for Science and Technology of Materials, Princeton University, Princeton, New Jersey 08544, United States.
⁴ Nordita, Stockholm University and KTH Royal Institute of Technology, Hannes Alfvéns väg 12, SE-106 91 Stockholm, Sweden.
⁵ Donostia International Physics Center, 20018 Donostia-San Sebastián, Spain.
⁶ Max Planck Institute for Chemical Physics of Solids, Dresden D-01187, Germany.
⁷ Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794, United States.
⁸ Center for Computational Quantum Physics, Flatiron Institute, New York, New York 10010, United States.

PMID: 36920080
DOI: 10.1021/acs.nanolett.2c05100

Abstract

Internal interfaces in Weyl semimetals (WSMs) are predicted to host distinct topological features that are different from the commonly studied external interfaces (crystal-to-vacuum boundaries). However, the lack of atomically sharp and crystallographically oriented internal interfaces in WSMs makes it difficult to experimentally investigate topological states buried inside the material. Here, we study a unique internal interface known as merohedral twin boundary in chemically synthesized single-crystal nanowires (NWs) of CoSi, a chiral WSM of space group P2₁3 (No. 198). Scanning transmission electron microscopy reveals that this internal interface is a (001) twin plane which connects two enantiomeric counterparts at an atomically sharp interface with inversion twinning. Ab initio calculations show localized internal Fermi arcs at the (001) twin plane that can be clearly distinguished from both external Fermi arcs and bulk states. These merohedrally twinned CoSi NWs provide an ideal platform to explore topological properties associated with internal interfaces in WSMs.

Keywords: CoSi nanowires; Fermi arcs; chiral Weyl semimetals; merohedral twinning; scanning transmission electron microscopy.