Issue 21, 2023

Novel two-dimensional magnets with an in-plane auxetic effect

Abstract

The auxetic effect in two-dimensional (2D) materials can not only enhance their mechanical properties but also brings additional tunability of their physical properties. Here, we employ density-functional-theory calculations to report on a class of auxetic 2D magnets, namely, the squarely packed transition metal dichlorides MCl2 (M = Ti, V, Mn, Fe, Co, Ni). These magnets are dynamically stable and exhibit an intrinsic in-plane auxetic effect. Meanwhile, the transition metal disulfides MS2 (M = V, Cr, Mn) with the same crystal structure exhibit a positive Poisson's ratio. This indicates that the auxetic effect in MCl2 is not merely dominated by the crystal structure. We attribute the occurrence of such auxetic behavior to the weak bond stiffness governed by electronic coupling between nearest-neighboring atoms. We find that magnetic ordering of 2D magnets with an auxetic effect is robust under external strain due to the protection of super-exchange interaction coming from the auxetic effect. Super-exchange interaction is sensitive to the symmetry of the crystal structure while the auxetic effect can mitigate the variation of such symmetry. The abundant magnetic properties in combination with the auxetic effect exhibit potential for novel nanodevice applications.

Graphical abstract: Novel two-dimensional magnets with an in-plane auxetic effect

Supplementary files

Article information

Article type
Paper
Submitted
29 Mar 2023
Accepted
24 Apr 2023
First published
24 Apr 2023

Nanoscale, 2023,15, 9365-9371

Novel two-dimensional magnets with an in-plane auxetic effect

R. Zhang, J. Pan, Y. Zhang and S. Du, Nanoscale, 2023, 15, 9365 DOI: 10.1039/D3NR01458D

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