Junji Yuhara

While theoretical studies predicted the stability and exotic properties of plumbene, the last group-14 cousin of graphene, its realization has remained a challenging quest. Here, it is shown with compelling evidence that plumbene is epitaxially grown by segregation on a Pd_1- _x Pb_x (111) alloy surface. In scanning tunneling microscopy (STM), it exhibits a unique surface morphology resembling the famous Weaire-Phelan bubble structure of the Olympic "WaterCube" in B

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 t

Large-scale two-dimensional sheets of graphene-like germanium, namely, germanene, have been epitaxially prepared on Ag(111) thin films grown on Ge(111), using a segregation method, differing from molecular beam epitaxy used in previous reports. From the scanning tunneling microscopy (STM) images, the surface is completely covered with an atom-thin layer showing a highly ordered long-range superstructure in wide scale. Two types of protrusions, named hexagon and line, form a (7√7 × 7√7) R19.1° su

Abstract Twenty five years after the first theoretical prediction of two-dimensional (2D) honeycomb-like silicon and germanium, now coined silicene and germanene, the last Group 14 artificial cousin of graphene has been synthesized, thus terminating the lineage from silicene (2012) to germanene (2014), stanene (2015), and finally plumbene (2019). Here, we describe the realizations and review the tantalizing properties of these outstanding novel 2D materials.

Abstract Group 14 elemental post‐graphene materials receive much attention because of their outstanding properties, typically, as robust 2D topological insulators. Their heterostructures are a main target in view of disruptive applications. Here, the realization of striking in‐plane lateral heterostructures between germanene and stanene are shown, which are sustainable 2D Ge‐ and Snbased graphene analogs, but with a strong intrinsic spin–orbit coupling. A unique combination of atomic segregation

We have analyzed the structure and composition of the first layer of an ${\text{Al}}_{72}{\text{Co}}_{16}{\text{Ni}}_{12}$ tenfold surface by means of scanning tunneling microscopy (STM), ion scattering spectroscopy (ISS), and Auger electron spectroscopy (AES). High-resolution STM images reveal local structures that have decagonal symmetry in addition to the usual pentagonal symmetry of the surface. This quasicrystal surface resembles a random tiling instead of an ideal quasiperiodic tiling. Aft

The single and binary metal films of Pb and Sn on Rh(111) have been studied at room temperature by scanning tunneling microscopy (STM), low-energy electron diffraction, and Auger electron spectroscopy. Both Pb and Sn are mobile at low coverage and form commensurate overlayers of (4\ifmmode\times\else\texttimes\fi{}4)-Pb and $c(2\ifmmode\times\else\texttimes\fi{}4)$-Sn, respectively. From atomically resolved STM images, the atomic arrangements of (4\ifmmode\times\else\texttimes\fi{}4)-Pb and $c(2

Isochronal annealing of Au–Ag binary adsorbates at the Si(111) surface at temperatures from 200 to 430 °C has been studied by means of low energy electron diffraction, Auger electron spectroscopy, and Rutherford backscattering spectroscopy techniques. It was found that a √3×√3−(Au,Ag) structure was formed by annealing for 15 min at 200 °C Ag atoms on the Si(111)–5×1-Au surface at Au coverages less than 0.60 ML, and that the √3×√3 structure was kept until Ag decreases from 0.70 ML down to 0.18 ML

The changes of the Au coverage and the structure of the Si(111)–√3×√3-Au surface induced by isothermal annealing in the temperature range of 500–575 °C have been studied by means of low-energy electron diffraction (LEED), Auger electron spectroscopy, and Rutherford backscattering spectroscopy techniques. It is found that the Au coverages by RBS and AES at each temperature decay exponentially down to 0.75 ML, above which only the LEED pattern of √3×√3 spots is observed, and decay biexponentially

Alternate annealing in the low- (≤250 °C) and high- (≥400 °C) temperature regimes of the Au/Si(111) surface at different Au coverages prepared by room-temperature deposition and isothermal annealing in the high-temperature regime at over-(ML) coverages have been studied by means of low energy electron diffraction (LEED), Auger electron spectroscopy (AES), and Rutherford backscattering spectroscopy (RBS). It is found that the 6×6 pattern and the √3×√3+satellite pattern are formed at 0.9–2.2 ML co

Abstract We have obtained single phase monolayer germanene on aluminum (111) thin films grown on a germanium (111) template by atomic segregation epitaxy, a preparation method differing from molecular beam epitaxy used in previous works. This 2 × 2 reconstructed germanene phase matching an Al(111)3 × 3 supercell has been prepared in large areas upon annealing at 430 °C. Detailed studies have been carried out using scanning tunneling microscopy (STM), low-energy electron diffraction, Auger electr

We studied the atomic arrangements and phase diagrams of two-dimensional (2D) Bi-Pb binary films on a Rh(111) surface with low-energy electron diffraction (LEED), scanning tunneling microscopy (STM), and Auger electron spectroscopy. The 2D binary films exhibited incommensurate (4 × 4) LEED patterns with any compositional ratio of Bi:Pb. Atomically resolved STM images revealed that the binary films formed hexagonal, close-packed structures in a 2D solid solution alloy. We found that the 2D binary