The thermal stability of a 2D metal: Structures and stability of gallenene

The recent discovery of two-dimensional (2D) gallium, in the form of metallic gallenene, has added to a long history of interest in the thermodynamic stability and structures of gallium. Despite research suggesting that two-dimensionality and surface stabilisation play an important role in both bulk and nanostructures of gallium, the properties and stability of different forms of 2D structures have remained unexplored. Through extensive density functional theory simulations, we investigate the structure and thermal stability of freestanding bilayer and trilayer gallenene. Our results show that reducing bulk gallium to two dimensions actually enhances the thermal stability. We also discover the origin of this intriguing result.