Issue 16, 2023

Vacancy-plane-mediated exfoliation of sub-monolayer 2D pyrrhotite

Abstract

Conventional exfoliation exploits the anisotropy in bonding or compositional character to delaminate 2D materials with large lateral size and atomic thickness. This approach, however, limits the choice to layered host crystals with a specific composition. Here, we demonstrate the exfoliation of a crystal along planes of ordered vacancies as a novel route toward previously unattainable 2D crystal structures. Pyrrhotite, a non-stoichiometric iron sulfide, was utilized as a prototype system due to its complex vacancy superstructure. Bulk pyrrhotite crystals were synthesized by gas-assisted bulk conversion, and their diffraction pattern revealed a 4C superstructure with 3 vacancy interfaces within the unit cell. Electrochemical intercalation and subsequent delamination yield ultrathin 2D flakes with a large lateral extent. Atomic force microscopy confirms that exfoliation occurs at all three supercell interfaces, resulting in the isolation of 2D structures with sub-unit cell thicknesses of 1/2 and 1/4 monolayers. The impact of controlling the morphology of 2D materials below the monolayer limit on 2D magnetic properties was investigated. Bulk pyrrhotite was shown to exhibit ferrimagnetic ordering that agrees with theoretical predictions and that is retained after exfoliation. A complex magnetic domain structure and an enhanced impact of vacancy planes on magnetization emphasize the potential of our synthesis approach as a powerful platform for modulating magnetic properties in future electronics and spintronics.

Graphical abstract: Vacancy-plane-mediated exfoliation of sub-monolayer 2D pyrrhotite

Supplementary files

Article information

Article type
Paper
Submitted
21 Apr 2023
Accepted
06 Jun 2023
First published
14 Jun 2023
This article is Open Access
Creative Commons BY-NC license

Nanoscale Adv., 2023,5, 4074-4079

Vacancy-plane-mediated exfoliation of sub-monolayer 2D pyrrhotite

J. Lee, Y. Chu, Z. Yen, J. Muthu, C. Ting, S. Huang, M. Hofmann and Y. Hsieh, Nanoscale Adv., 2023, 5, 4074 DOI: 10.1039/D3NA00263B

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