title: Buckled two-dimensional Xene sheets.
abstract: Silicene, germanene and stanene are part of a monoelemental class of two-dimensional (2D) crystals termed 2D-Xenes (X = Si, Ge, Sn and so on) which, together with their ligand-functionalized derivatives referred to as Xanes, are comprised of group IVA atoms arranged in a honeycomb lattice - similar to graphene but with varying degrees of buckling. Their electronic structure ranges from trivial insulators, to semiconductors with tunable gaps, to semi-metallic, depending on the substrate, chemical functionalization and strain. More than a dozen different topological insulator states are predicted to emerge, including the quantum spin Hall state at room temperature, which, if realized, would enable new classes of nanoelectronic and spintronic devices, such as the topological field-effect transistor. The electronic structure can be tuned, for example, by changing the group IVA element, the degree of spin-orbit coupling, the functionalization chemistry or the substrate, making the 2D-Xene systems promising multifunctional 2D materials for nanotechnology. This Perspective highlights the current state of the art and future opportunities in the manipulation and stability of these materials, their functions and applications, and novel device concepts.
authors.affiliation: Laboratorio MDM, IMM-CNR, via C. Olivetti 2, Agrate Brianza I-20864, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Molle
authors.affiliation: Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, USA.
authors.forename: Joshua
authors.initials: J
authors.lastname: Goldberger
authors.affiliation: Department of Physics and Astronomy, University of Leuven, B-3001 Leuven, Belgium.
authors.forename: Michel
authors.initials: M
authors.lastname: Houssa
authors.affiliation: State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China.|Collaborative Innovation Center of Quantum Matter, Beijing 100084, China.|RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan.
authors.forename: Yong
authors.initials: Y
authors.lastname: Xu
authors.affiliation: Department of Physics, McCullough Building, Stanford University, Stanford, California 94305-4045, USA.|Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.|Institute for Advanced Study, Tsinghua University, Beijing 100084, China.
authors.forename: Shou-Cheng
authors.initials: SC
authors.lastname: Zhang
authors.affiliation: Microelectronics Research Center, The University of Texas at Austin, Texas 78758, USA.
authors.forename: Deji
authors.initials: D
authors.lastname: Akinwande