Beyond Graphene: Low-Symmetry and Anisotropic 2D Materials

TL;DR

This paper reviews recent experimental and theoretical advances in low-symmetry 2D materials, highlighting their unique properties and potential applications due to their complex structures and reduced symmetries.

Contribution

It provides a comprehensive overview of the emerging low-symmetry 2D materials, emphasizing their novel properties and recent research developments.

Findings

Low-symmetry 2D materials exhibit inhomogeneous electronic and optical responses.

Emerging properties include ferroelasticity, ferroelectricity, and superconductivity.

Recent studies reveal potential for novel applications in electronics and photonics.

Abstract

Low-symmetry 2D materials---such as ReS$_2$ and ReSe$_2$ monolayers, black phosphorus monolayers, group-IV monochalcogenide monolayers, borophene, among others---have more complex atomistic structures than the honeycomb lattices of graphene, hexagonal boron nitride, and transition metal dichalcogenides. The reduced symmetries of these emerging materials give rise to inhomogeneous electron, optical, valley, and spin responses, as well as entirely new properties such as ferroelasticity, ferroelectricity, magnetism, spin-wave phenomena, large nonlinear optical properties, photogalvanic effects, and superconductivity. Novel electronic topological properties, nonlinear elastic properties, and structural phase transformations can also take place due to low symmetry. The "Beyond Graphene: Low-Symmetry and Anisotropic 2D Materials" Special Topic was assembled to highlight recent experimental and theoretical research on these emerging materials.