Nav: Home

2-D tin (stanene) without buckling: A possible topological insulator

January 19, 2018

Nagoya University-led researchers produce 2D sheets of tin atoms predicted to have exotic uses in electronics.

Nagoya, Japan - Sometimes it pays to be two-dimensional. The merits of graphene, a 2D sheet of carbon atoms, are well established. In its wake have followed a host of "post-graphene materials" - structural analogues of graphene made of other elements like silicon or germanium.

Now, an international research team led by Nagoya University (Japan) involving Aix-Marseille University (France), the Max Planck Institute in Hamburg (Germany) and the University of the Basque country (Spain) has unveiled the first truly planar sample of stanene: single sheets of tin (Sn) atoms. Planar stanene is hotly tipped as an extraordinary electrical conductor for high technology.

Just as graphene differs from ordinary graphite, so does stanene behave very differently to humble tin in bulk form. Because of relatively strong spin-orbit interactions for electrons in heavy elements, single-layer tin is predicted to be a "topological insulator," also known as a quantum spin Hall (QSH) insulator. Materials in this remarkable class are electrically insulating in their interiors, but have highly conductive surfaces/edges. This, in theory, makes a single-layered topological insulator an ideal wiring material for nanoelectronics. Moreover, the highly conductive channels at the edge of these materials can carry special chiral currents with spins locked with transport directions, which makes them also very appealing for spintronics applications.

In previous studies, where stanene was grown on substrates of bismuth telluride or antimony, the tin layers turned out to be highly buckled and relatively inhomogeneous. The Nagoya team instead chose silver (Ag) as their host - specifically, the Ag(111) crystal facet, whose lattice constant is slightly larger than that of the freestanding stanene, leading to the formation of flattened tin monolayer in a large area, one step closer to the scalable industrial applications.

Individual tin atoms were slowly deposited onto silver, known as epitaxial growth. Crucially, the stanene layer did not form directly on top of the silver surface. Instead, as shown by core-level spectroscopy, the first step was the formation of a surface alloy (Ag2Sn) between the two species. Then, another round of tin deposition produced a layer of pure, highly crystalline stanene atop the alloy. Tunneling microscopy shows striking images of a honeycomb lattice of tin atoms, illustrating the hexagonal structure of stanene.

The alloy guaranteed the flatness of the tin layer, as confirmed by density-functional theory calculations. Junji Yuhara, lead author of an article by the team published in 2D Materials, explains: "Stanene follows the crystalline periodicity of the Ag2Sn surface alloy. Therefore, instead of buckling as it would in isolation, the stanene layer flattens out - at the cost of a slight strain - to maximize contact with the alloy beneath." This mutual stabilization between stanene and host not only keeps the stanene layers impeccably flat, but lets them grow to impressive sizes of around 5,000 square nanometers.

Planar stanene has exciting prospects in electronics and computing. "The QSH effect is rather delicate, and most topological insulators only show it at low temperatures", according to project team leader Guy Le Lay at Aix-Marseille University. "However, stanene is predicted to adopt a QSH state even at room temperature and above, especially when functionalized with other elements. In the future, we hope to see stanene partnered up with silicene in computer circuitry. That combination could drastically speed up computational efficiency, even compared with the current cutting-edge technology."
-end-
The article, "Large area planar stanene epitaxially grown on Ag(111)," was published in 2D Materials at DOI:10.1088/2053-1583/aa9ea0.

Nagoya University

Related Graphene Articles:

New chemical method could revolutionize graphene
University of Illinois at Chicago scientists have discovered a new chemical method that enables graphene to be incorporated into a wide range of applications while maintaining its ultra-fast electronics.
Searching beyond graphene for new wonder materials
Graphene, the two-dimensional, ultra lightweight and super-strong carbon film, has been hailed as a wonder material since its discovery in 2004.
New method of characterizing graphene
Scientists have developed a new method of characterizing graphene's properties without applying disruptive electrical contacts, allowing them to investigate both the resistance and quantum capacitance of graphene and other two-dimensional materials.
Chemically tailored graphene
Graphene is considered as one of the most promising new materials.
Beyond graphene: Advances make reduced graphene oxide electronics feasible
Researchers have developed a technique for converting positively charged (p-type) reduced graphene oxide (rGO) into negatively charged (n-type) rGO, creating a layered material that can be used to develop rGO-based transistors for use in electronic devices.
The Graphene 2017 Conference connects Barcelona with the international graphene-based industry
This prestigious Conference to be held at the Barcelona International Convention Centre (March 28-31) aims to bring together academia and industry to integrate new graphene technologies into practical applications.
Graphene from soybeans
A breakthrough by CSIRO-led scientists has made the world's strongest material more commercially viable, thanks to the humble soybean.
First use of graphene to detect cancer cells
By interfacing brain cells onto graphene, researchers at the University of Illinois at Chicago have shown they can differentiate a single hyperactive cancerous cell from a normal cell, pointing the way to developing a simple, noninvasive tool for early cancer diagnosis.
Development of graphene microwave photodetector
DGIST developed cryogenic microwave photodetector which is able to detect 100,000 times smaller light energy compared to the existing photedetectors.
Adding hydrogen to graphene
IBS researchers report a fundamental study of how graphene is hydrogenated.

Related Graphene Reading:

Graphene: The Superstrong, Superthin, and Superversatile Material That Will Revolutionize the World
by Les Johnson (Author), Joseph E. Meany (Author)

Two scientists give an enthusiastic, layperson's overview of a new supermaterial now in development that could transform many features of daily life, from creating new conveniences to improving health and safety.

What if you discovered an infinitesimally thin material capable of conducting electricity, able to suspend millions of times its own weight, and yet porous enough to filter the murkiest water? And what if this incredible substance is created from the same element that fills the common pencil? That's graphene--a flat, two-dimensional, carbon-based molecule with a single... View Details


The Chemistry Book: From Gunpowder to Graphene, 250 Milestones in the History of Chemistry (Sterling Milestones)
by Derek B Lowe (Author)

NA View Details


Graphene: Fundamentals and emergent applications
by Jamie H. Warner (Author), Franziska Schaffel (Author), Mark Rummeli (Author), Alicja Bachmatiuk (Author)

Providing fundamental knowledge necessary to understand graphene’s atomic structure, band-structure, unique properties and an overview of groundbreaking current and emergent applications, this new handbook is essential reading for materials scientists, chemists and physicists.

Since the 2010 physics Nobel Prize awarded to Geim and Novosolev for their groundbreaking work isolating graphene from bulk graphite, there has been a huge surge in interest in the area. This has led to a large number of news books on graphene. However, for such a vast inflow of new entrants, the current... View Details


Graphene: An Introduction to the Fundamentals and Industrial Applications (Advanced Material Series)
by Madhuri Sharon (Editor), Maheshwar Sharon (Editor), Ashutosh Tiwari (Editor), Hisanori Shinohara (Editor)

Often described as a “miracle material”, graphene’s potential applications are extraordinary, ranging from nanoscale ‘green’ technologies, to sensors and future conductive coatings.

This book covers the topic of ‘graphene’ – the history, fundamental properties,  methods of production and applications of this exciting new material. The style of the book is both scientific and technical – it is accessible to an audience that has a general, undergraduate-level background in the sciences or engineering, and is aimed at industries considering graphene applications.

... View Details


Graphene: A New Paradigm in Condensed Matter and Device Physics
by E. L. Wolf (Author)

The book is an introduction to the science and possible applications of Graphene, the first one-atom-thick crystalline form of matter. Discovered in 2004 by now Nobelists Geim and Novoselov, the single layer of graphite, a hexagonal network of carbon atoms, has astonishing electrical and mechanical properties. It supports the highest electrical current density of any material, far exceeding metals copper and silver. Its absolute minimum thickness, 0.34 nanometers, provides an inherent advantage in possible forms of digital electronics past the era of Moore's Law.

The book describes the... View Details


Graphene: Fundamentals, Devices, and Applications
by Serhii Shafraniuk (Author)

Graphene is the first example of two-dimensional materials and is the most important growth area of contemporary research. It forms the basis for new nanoelectronic applications. Graphene, which comprises field-effect structures, has remarkable physical properties.

This book focuses on practical applications determined by the unique properties of graphene. Basic concepts are elucidated by end-of-chapter problems, the answers to which are provided in the accompanying solutions manual. The mechanisms of electric and thermal transport in the gated graphene, interface phenomena,... View Details


Graphene: Carbon in Two Dimensions
by Mikhail I. Katsnelson (Author)

Graphene is the thinnest known material, a sheet of carbon atoms arranged in hexagonal cells a single atom thick, and yet stronger than diamond. It has potentially significant applications in nanotechnology, 'beyond-silicon' electronics, solid-state realization of high-energy phenomena and as a prototype membrane which could revolutionise soft matter and 2D physics. In this book, leading graphene research theorist Mikhail Katsnelson presents the basic concepts of graphene physics. Topics covered include Berry phase, topologically protected zero modes, Klein tunneling, vacuum reconstruction... View Details


Graphene: Energy Storage and Conversion Applications (Electrochemical Energy Storage and Conversion)
by Zhaoping Liu (Author), Xufeng Zhou (Author)

Suitable for readers from broad backgrounds, Graphene: Energy Storage and Conversion Applications describes the fundamentals and cutting-edge applications of graphene-based materials for energy storage and conversion systems. It provides an overview of recent advancements in specific energy technologies, such as lithium ion batteries, supercapacitors, fuel cells, solar cells, lithium sulfur batteries, and lithium air batteries. It also considers the outlook of industrial applications in the near future. Offering a brief introduction to the major synthesis methods of graphene, the... View Details


Graphene
by Caravan Publishing

A scientific genius escapes from Soviet Russia with his wife. They have nothing, but the help of a stranger starts him on his way to accumulating a fortune, with a steady flow of inventions. He finds graphene, a miracle material that has almost unimaginable qualities, but can only be extracted in minute quantities. Leonid sees the potential of the product for the entire world and, together with Marina, his daughter, he develops a means to produce the material cheaply enough to compete with almost every existing product that it can replace. He fails to reckon with big business, and the... View Details


Graphene: Fabrication, Characterizations, Properties and Applications
by Hongwei Zhu (Author)

Graphene: Fabrication, Characterizations, Properties and Applications presents a comprehensive review of the current status of graphene, especially focused on synthesis, fundamental properties and future applications, aiming to giving a comprehensive reference for scientists, researchers and graduate students from various sectors. Graphene, a single atomic layer of carbon hexagons, has stimulated a lot of research interest owing to its unique structure and fascinating properties.

The book is devoted to understanding graphene fundamentally yet comprehensively through a wide... View Details

Best Science Podcasts 2018

We have hand picked the best science podcasts for 2018. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Attention Please
In an age of constant information and infinite distractions, how can we pay more attention to our ... attention? This hour, TED speakers explore the battle for our awareness during the digital age. Guests include sociologist Zeynep Tufekci, podcast host Manoush Zomorodi, neuroscientist Amishi Jha, designer Tristan Harris, and computer scientist Jaron Lanier.
Now Playing: Science for the People

#475 Mother Nature is Trying to Kill You (Rebroadcast)
This week, we're learning how deadly and delightful our planet and its ecosystem can be. We're joined by biologist Dan Riskin, co-host of Discovery Canada's Daily Planet, to talk about his book "Mother Nature Is Trying to Kill You: a Lively Tour Through the Dark Side of the Natural World." And we'll talk to astronomer and author Phil Plait about Science Getaways, his company that offers educational vacation experiences for science lovers.