title: Three-fold rotational defects in two-dimensional transition metal dichalcogenides.
abstract: As defects frequently govern the properties of crystalline solids, the precise microscopic knowledge of defect atomic structure is of fundamental importance. We report a new class of point defects in single-layer transition metal dichalcogenides that can be created through 60° rotations of metal-chalcogen bonds in the trigonal prismatic lattice, with the simplest among them being a three-fold symmetric trefoil-like defect. The defects, which are inherently related to the crystal symmetry of transition metal dichalcogenides, can expand through sequential bond rotations, as evident from in situ scanning transmission electron microscopy experiments, and eventually form larger linear defects consisting of aligned 8-5-5-8 membered rings. First-principles calculations provide insights into the evolution of rotational defects and show that they give rise to p-type doping and local magnetic moments, but weakly affect mechanical characteristics of transition metal dichalcogenides. Thus, controllable introduction of rotational defects can be used to engineer the properties of these materials.
authors.affiliation: National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8565, Japan.
authors.forename: Yung-Chang
authors.initials: YC
authors.lastname: Lin
authors.affiliation: COMP/Department of Applied Physics, Aalto University, P.O. Box 11100, FI-00076 Aalto, Finland.
authors.forename: Torbjörn
authors.initials: T
authors.lastname: Björkman
authors.affiliation: COMP/Department of Applied Physics, Aalto University, P.O. Box 11100, FI-00076 Aalto, Finland.
authors.forename: Hannu-Pekka
authors.initials: HP
authors.lastname: Komsa
authors.affiliation: Department of Electronic Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan.
authors.forename: Po-Yuan
authors.initials: PY
authors.lastname: Teng
authors.affiliation: Department of Electronic Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan.
authors.forename: Chao-Hui
authors.initials: CH
authors.lastname: Yeh
authors.affiliation: Department of Electronic Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan.
authors.forename: Fei-Sheng
authors.initials: FS
authors.lastname: Huang
authors.affiliation: Department of Electronic Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan.
authors.forename: Kuan-Hung
authors.initials: KH
authors.lastname: Lin
authors.affiliation: Institute of Physics, Wrocław University of Technology, Wyb. Wyspiańskiego 27, 50-370 Wrocław, Poland.
authors.forename: Joanna
authors.initials: J
authors.lastname: Jadczak
authors.affiliation: Department of Electronic Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan.
authors.forename: Ying-Sheng
authors.initials: YS
authors.lastname: Huang
authors.affiliation: Department of Electronic Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan.
authors.forename: Po-Wen
authors.initials: PW
authors.lastname: Chiu
authors.affiliation: Department of Applied Physics, Aalto University, P.O. Box 11100, FI-00076 Aalto, Finland.
authors.forename: Arkady V
authors.initials: AV
authors.lastname: Krasheninnikov
authors.affiliation: National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8565, Japan.
authors.forename: Kazu
authors.initials: K
authors.lastname: Suenaga
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