[GS_C_MS] Nonlocal disorder in graphene: from topological defects to amorphous state
ABSTRACT
Dislocations and grain boundaries are intrinsic topological defects in polycrystalline materials that inevitably affect their physical properties. In my talk, I will discuss topological defects in 2D materials [1], taking graphene as a prototypical example. I will first introduce a general approach to constructing the atomic structure of such defects eventually establishing a connection to homotopy theory. First-principles calculations of the thermodynamic properties of grain boundaries reveal energetically favorable large-angle configurations and dramatic stabilization of small-angle configurations via out-of-plane deformation [2]. Both the presence of stable large-angle grain-boundary motifs and the out-of-plane deformation of small-angle configurations have been observed by scanning tunneling microscopy [3]. Electronic transport in the presence of topological defects also exhibits several intriguing features [4–6]. In the second half of my talk, I will present more recent results on monolayer amorphous carbon [7], a system that can be viewed as polycrystalline graphene in the limit of grain size approaching the lattice constant. This highly disordered 2D material is very different from pristine graphene, and many of its properties turn out to be interesting both from the point of view of fundamental physics, such as the observed multifractal scaling of the electronic states [8], as well as applications in catalysis, batteries, etc. (see Refs. [9,10] and a number of manuscripts in progress).
[1] O. V. Yazyev and Y. P. Chen, Nature Nanotechnol. 9, 755 (2014).
[2] O. V. Yazyev and S. G. Louie, Phys. Rev. B 81, 195420 (2010).
[3] Y. Tison et al., Nano Lett. 14, 6382 (2014).
[4] O. V. Yazyev and S. G. Louie, Nature Mater. 9, 806 (2010).
[5] J. H. Chen et al., Phys. Rev. B 89, 121407 (2014).
[6] F. Gargiulo and O. V. Yazyev, Nano Lett. 14, 250 (2014).
[7] C. T. Toh et al., Nature 577, 199 (2020).
[8] Rejaul SK et al., arXiv:2605.14349 (2026).
[9] H. Zhang et al., Adv. Mater. 37, 2419112 (2025).
[10] L. Shi et al., Adv. Sci. 13, e16490 (2026).
