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Lookup NU author(s): Dr Charlie McMonagleORCiD, Professor Mike ProbertORCiD
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
© 2025 Elsevier Inc. Bespoke van der Waals (vdW) crystals provide command over the confinement and transport of charge, spin, and heat within and between two-dimensional (2D) layers. We report a novel functionality in vdW crystals by actuating valence changes through molecular alloying. The net materials Cr(pyrazine)2Br2 and Cr(pyrazine)2I2 are aliovalent, hosting Cr(III) and Cr(II), respectively, due to disparate crystal field potentials. Pressurizing and thereby strengthening of the crystal field compresses the Cr(pyrazine)2I2 layers significantly, but no Cr valence change is induced. However, alloyed Cr(pyrazine)2I2−xBrx phases exhibit hysteretic and tunable Cr(II) ⇄ Cr(III) interconversions with concomitant charge injection into the net. The valence switch manifests drastic changes to the magnetization and the electrical conductivity, which varies by up to five orders of magnitude during the valence conversion. This use of coordination chemistry addresses a gap in vdW and 2D materials science, where electronic structure engineering via valence change events has remained elusive.
Author(s): Aribot F, Voigt L, Dunstan MA, Wan W, McPherson JN, Kubus M, Yutronkie NJ, McMonagle CJ, Coletta M, Manvell AS, Perlepe P, Viborg A, Wong S, Stampe KA, Baran V, Senyshyn A, Deylamani ST, Le MD, Walker HC, Chanda A, Trier F, Pryds N, Wilhelm F, Jinschek JR, Pinkowicz D, Probert MR, Clerac R, Christensen NB, Brechin EK, Rogalev A, Pedersen KS
Publication type: Article
Publication status: Published
Journal: Chem
Year: 2025
Pages: epub ahead of print
Online publication date: 28/04/2025
Acceptance date: 04/04/2025
Date deposited: 16/05/2025
ISSN (print): 2451-9308
ISSN (electronic): 2451-9294
Publisher: Elsevier Inc.
URL: https://doi.org/10.1016/j.chempr.2025.102557
DOI: 10.1016/j.chempr.2025.102557
ePrints DOI: 10.57711/2vcc-ys29
Data Access Statement: Crystallographic data for the structures reported in this article have been deposited at the Cambridge Crystallographic Data Centre, under deposition numbers CCDC 2367722–2367739. Copies of the data can be obtained free of charge via https://www.ccdc.cam.ac.uk/structures/. Raw INS data are available at https://doi.org/10.5286/ISIS.E.RB1920693
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