Abstract
Artificial post-graphene elemental 2D materials have received much attention recently. Especially, stanene, the tin analogue of graphene, is expected to be a robust 2D topological insulator, even above room temperature. We have grown epitaxial 2D stanene on a Ag(1 1 1) single crystal template and determined its crystalline structure synergetically by scanning tunneling microscopy, high-resolution synchrotron radiation photoemission spectroscopy, and advanced first principles calculations. From the STM images, we show that stanene forms a nearly planar structure in large domains. A detailed core-level spectroscopy analysis as well as DFT calculations reveal that the stanene sheet lays over an ordered 2D Ag2Sn surface alloy, but not directly on a bulk-terminated Ag(1 1 1) surface. The electronic structure exhibits a characteristic 2D band with parabolic dispersion due to the non-negligible interaction with the underlying surface alloy.
Highlights
Post-graphene two-dimensional (2D) elemental honeycomb lattices have received much attention recently [1], because they are expected to host novel striking properties like the quantum spin Hall (QSH) effect [2, 3] and amenability to band gap engineering [4]
We report the epitaxial growth of well-ordered, large area, planar stanene prepared by Sn deposition onto Ag(1 1 1)
We examined the crystalline structure using low-energy electron diffraction (LEED), scanning tunneling microscopy (STM), synchrotron radiation core-level spectroscopy (CLS), angle-resolved photoemission spectroscopy (ARPES), along with advanced density functional theory (DFT) calculations of the geometry, shallow core-level (CL) chemical shifts, and stability of the system
Summary
Post-graphene two-dimensional (2D) elemental honeycomb lattices have received much attention recently [1], because they are expected to host novel striking properties like the quantum spin Hall (QSH) effect [2, 3] and amenability to band gap engineering [4] Silicene and germanene, such post-graphene materials, had been theoretically predicted by Takeda and Shiraishi in 1994 [5]. Unique physical properties for stanene have been predicted, such as the QSH effect [13, 14], topological superconductivity [15], giant magnetoresistance [16], perfect spin filter [16], and anomalous Seebeck effect [17] All these properties are based on low-buckled stanene. We use a single crystal of Ag(1 1 1) as a substrate, as suggested by Gao et al [12], because the lattice constants of Ag(1 1 1) and Au(1 1 1) are very close and the clean Ag(1 1 1) surface does not form a superstructure
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