Nanotechnology Now

Our NanoNews Digest Sponsors



Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Topological insulators: Breaking symmetry for faster computers

Electronic structures of BiTeCl's top and bottom crystal surfaces observed by photoemission spectroscopy.
Electronic structures of BiTeCl's top and bottom crystal surfaces observed by photoemission spectroscopy.

Abstract:
A new compound developed at Tokyo Tech shows highly unusual conducting properties that could be used in future electronic components. The details are described in the November 2013 issue of Tokyo Institute of Technology Bulletin: www.titech.ac.jp/english/news/2013/024244.html

Topological insulators: Breaking symmetry for faster computers

Tokyo, Japan | Posted on November 25th, 2013

Ordinary insulating solids, such as diamond, have energy bands that are fully occupied by electrons. The conducting band is so far away from the valence band in diamond that electrons do not have sufficient energy to move - the ‘band gap' is large - therefore no electric current can be carried.

In recent years, researchers have become interested in materials called topological insulators (TIs), which act as insulators on the inside, but are highly conductive on their surfaces. In TIs, an exceptionally strong spin-orbit interaction inverts the energy gap between occupied and empty states, so that electrons at the surface can flow across the gap. These properties are intrinsic to the material, meaning a TI remains conductive even if its surface is not perfect.

Now, an international team of scientists from Japan, the UK and the USA, led by Takao Sasagawa at Tokyo Institute of Technology, have successfully developed a new TI from bismuth, tellurium and chlorine (BiTeCl). Their new TI is inversion asymmetric, meaning it has different electronic states, and therefore different polarities, on each crystal surface. As a result, it exhibits many topological effects that have not been seen experimentally before.

"The metallic surface state of a TI is similar to graphene in that the electron mobility is remarkably high due to zero-mass electrons, or Dirac fermions," explains Sasagawa. "The Dirac fermions have a characteristic spin and in this context they can host a wide range of exotic quantum phenomena. Symmetry-breaking is the best way of inducing these fascinating topological effects."

Sasagawa and his team optimised their laboratory growing conditions to produce single crystals of BiTeCl. They then split each single crystal to obtain two different surfaces - one Te and one Cl - and observed their electronic structures using spectroscopy. The composition of the TI's top and bottom crystal surfaces are such that their charge carriers are opposite, leading to polarization. The TI can therefore be used as a diode, allowing current flow in only one direction. It also exhibits pyroelectric capabilities, meaning that it can generate a temporary voltage when heated or cooled.

BiTeCl shows promise as a platform for other topological phenomena, and may have applications at high temperatures. The discovery could also have significant implications for the development of quantum-based technologies in future, as Sasagawa explains: "We would like to discover a topological superconductor whose surface can host Majorana fermions - particles which are their own antiparticles, and could be used for the development of topological quantum computing."

Reference

Y.L.Chen, M. Kanou, Z.-X. Shen, T. Sasagawa et al. Discovery of a single topological Dirac fermion in the strong inversion asymmetric compound BiTeCl. Nature Physics Published online: 6 October 2013 doi: 10.1038/NPHYS2768

####

About Tokyo Institute of Technology
As one of Japan’s top universities, Tokyo Institute of Technology seeks to contribute to civilization, peace and prosperity in the world, and aims at developing global human capabilities par excellence through pioneering research and education in science and technology, including industrial and social management. To achieve this mission, we have an eye on educating highly moral students to acquire not only scientific expertise but also expertise in the liberal arts, and a balanced knowledge of the social sciences and humanities, all while researching deeply from basics to practice with academic mastery. Through these activities, we wish to contribute to global sustainability of the natural world and the support of human life.

For more information, please click here

Contacts:
Miwako Kato
Yukiko Tokida
Center for Public Information
Tokyo Institute of Technology, 2-12-1, Ookayama, Meguro-ku
Tokyo 152-8550, Japan

Tel: +81-3-5734-2975
Fax: +81-3-5734-3661

Copyright © Tokyo Institute of Technology

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

SEMATECH to Showcase Innovation and Advances in Manufacturing at SEMICON Japan 2014: SEMATECH experts will share the latest techniques, emerging trends and best practices in advanced manufacturing strategies and methodologies November 26th, 2014

Australian startup creates world’s first 100% cotton hydrophobic T-Shirts November 26th, 2014

The mysterious 'action at a distance' between liquid containers November 26th, 2014

'Giant' charge density disturbances discovered in nanomaterials: Juelich researchers amplify Friedel oscillations in thin metallic films November 26th, 2014

Chip Technology

SEMATECH to Showcase Innovation and Advances in Manufacturing at SEMICON Japan 2014: SEMATECH experts will share the latest techniques, emerging trends and best practices in advanced manufacturing strategies and methodologies November 26th, 2014

'Giant' charge density disturbances discovered in nanomaterials: Juelich researchers amplify Friedel oscillations in thin metallic films November 26th, 2014

Nanometrics Announces Upcoming Investor Events November 19th, 2014

A novel method for identifying the body’s ‘noisiest’ networks November 19th, 2014

Quantum Computing

Pseudospin-driven spin relaxation mechanism in graphene November 11th, 2014

Heat Transfer Sets the Noise Floor for Ultrasensitive Electronics November 11th, 2014

Noise in a microwave amplifier is limited by quantum particles of heat November 10th, 2014

Sussex physicists find simple solution for quantum technology challenge October 28th, 2014

Discoveries

The mysterious 'action at a distance' between liquid containers November 26th, 2014

'Giant' charge density disturbances discovered in nanomaterials: Juelich researchers amplify Friedel oscillations in thin metallic films November 26th, 2014

Vegetable oil ingredient key to destroying gastric disease bacteria: In mice, therapeutic nanoparticles dampen H. pylori bacteria and inflammation that lead to ulcers and gastric cancer November 25th, 2014

Research yields material made of single-atom layers that snap together like Legos November 25th, 2014

Announcements

SEMATECH to Showcase Innovation and Advances in Manufacturing at SEMICON Japan 2014: SEMATECH experts will share the latest techniques, emerging trends and best practices in advanced manufacturing strategies and methodologies November 26th, 2014

Australian startup creates world’s first 100% cotton hydrophobic T-Shirts November 26th, 2014

The mysterious 'action at a distance' between liquid containers November 26th, 2014

'Giant' charge density disturbances discovered in nanomaterials: Juelich researchers amplify Friedel oscillations in thin metallic films November 26th, 2014

Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers

The mysterious 'action at a distance' between liquid containers November 26th, 2014

'Giant' charge density disturbances discovered in nanomaterials: Juelich researchers amplify Friedel oscillations in thin metallic films November 26th, 2014

Vegetable oil ingredient key to destroying gastric disease bacteria: In mice, therapeutic nanoparticles dampen H. pylori bacteria and inflammation that lead to ulcers and gastric cancer November 25th, 2014

Research yields material made of single-atom layers that snap together like Legos November 25th, 2014

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More












ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE