Efros-Shklovskii Law at the Thinnest Limit of a Material.

Denisov, N V; Vekovshinin, Y E; Bondarenko, L V; Zotov, A V; Saranin, A A · Nano Lett · 2026

basic_science · Level V

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Abstract

For a half-century, the Efros-Shklovskii (ES) law has been a powerful framework for describing conduction in disordered systems featuring a Coulomb gap. Here, we examined the validity of the ES law at the ultimate 2D thickness limit by investigating the low-temperature transport of three single-atom-thick crystalline systems based on the √3×√3-Au reconstruction on a Si(111) surface. Structural disorder was represented by three distinct configurations: (i) random network of domain walls (α-Au phase), (ii) inhomogeneous Au-Cu solid solution, and (iii) random 2D gas of Tl adatoms atop the crystalline layer. We found that only the domain-wall-disordered α-Au phase exhibits temperature dependence of the conduction described by the ES law. In contrast, the other two configurations display typical metallic behavior.