Atlas for the properties of elemental two-dimensional metals

Abstract

Common two-dimensional (2D) materials have a layered 3D structure with covalently bonded, atomically thin layers held together by weak van der Waals forces. However, in a recent transmission electron microscopy experiment, atomically thin 2D patches of iron were discovered inside a graphene nanopore. Motivated by this discovery, we perform a systematic density-functional study on atomically thin elemental 2D metal films, using 45 metals in three lattice structures. Cohesive energies, equilibrium distances, and bulk moduli in 2D are found to be linearly correlated to the corresponding 3D bulk properties, enabling the quick estimation of these values for a given 2D metal and lattice structure. In-plane elastic constants show that most 2D metals are stable in hexagonal and honeycomb, but unstable in square 2D structures. Many 2D metals are surprisingly stable against bending.

Emerging Applications of Elemental 2D Materials

“…Mater. 2020, 32,1904302 3.0 Attribution 3.0 Unported License (https://creativecommons.org/licenses/by/3.0/). [42] Copyright 2018, IOP Publishing Ltd. j-n) Reproduced with permission.…”

“…Mater. 2020, 32,1904302 insulating behavior (see below) with a predicted spin-orbit monolayer bandgap of ≈0.3 eV [26,52] and measured bandgap of 0.67 eV, [26] which disappears in multilayer bismuthene as it becomes metallic. In group VI elements, αand β-tellurene (see Figure 2) has been predicted to have a "nearly direct" and direct bandgap of 0.75 and 1.47 eV, respectively.…”

“…While many of these were hypothesized to exist prior to the “reawakening” of 2D materials triggered by the initial work on graphene, recent work in the 2D materials field has shaped the future of these atomically thin materials. Last, note that this review discussion focuses specifically on the main group elements and does not explicitly discuss 2D elemental transition metals, which were reviewed elsewhere recently …”

“…Last, note that this review discussion focuses specifically on the main group elements and does not explicitly discuss 2D elemental transition metals, which were reviewed elsewhere recently. [5,32] Motivated by recent advances in the exciting class of main group elemental materials, herein we review the application literature to date, connect the crystal structure of various elemental 2D materials to their measured/predicted properties, and identify their strengths and weaknesses for applications including electronics, spintronics, optoelectronics, energy conversion, and more.…”

High Bipolar Conductivity and Robust In‐Plane Spontaneous Electric Polarization in Selenene

“…Fortunately, more and more atomic thickness spontaneous electric polarization has been discovered in ionic compound monolayer with the puckered lattice structure. [16,17] Among elemental 2D materials, group-VI elements have been predicted and successfully fabricated at last year. [4][5][6][7] Fascinatingly more, ferroelectricity was also discovered in the 2D elemental materials, such as phosphorene nanoribbons, [8] group-V (As, Sb, Bi) monolayer [9] and tellurium multilayers, [10] which was previously thought impossible because of the stabilized high symmetry in elemental bulk structures and the equal distribution of charge per atom.…”