Featured Research

from universities, journals, and other organizations

Novel topological crystalline insulator shows mass appeal

Date:
August 29, 2013
Source:
Boston College
Summary:
Physicists have theorized that topological crystalline insulators possess unique surface states as a result of crystalline symmetry. An international team of researchers has confirmed that experimental signature and revealed that disrupting the lattice-like structure imparts mass upon previously mass-less electrons. Furthermore, the researchers found manipulating structural symmetry offers a degree of control over the electronic phases of the solid-state material.

Disrupting the symmetrical structure of a solid-state topological crystalline insulator creates mass in previously mass-less electrons and imparts an unexpected level of control in this nascent class of materials, an international team of researchers reports in the current edition of Science Express.

The researchers not only confirmed several theoretical predictions about topological crystalline insulators (TCIs), but made a significant experimental leap forward that revealed even more details about the crystal structure and electronic behavior of these newly identified materials, according to Boston College Associate Professor of Physics Vidya Madhavan, one of the lead authors of the report.

The findings could pave the way for engineering the electronic properties of TCI surfaces towards novel functionalities at the nanoscale.

"There is a lot of rich physics here that's waiting to be explored," said Madhavan. "We've opened the door to better understanding topological crystalline insulators and the potential of these materials."

Confirmed within the past few years, topological insulators possess interiors that behave like insulators, blocking the flow of electrons. Yet externally, they contain conducting states where electrons can move freely across their surfaces. A few years ago, physicists first posited the existence of TCIs, a new class of topological materials where conducting surface electrons are theorized to obey fundamental quantum laws set by the crystalline structure of the interior.

Starting with a TCI consisting of lead and selenium, researchers sought to disrupt its structural symmetry by provoking, or doping, the material through the addition of tin, Madhavan said. The subsequent disruption had a dramatic effect on mass-less "Dirac" electrons that are present within the material and behave as relativistic particles. The manipulation added mass to some of these electrons, which took their places side-by-side with the Dirac electrons, a startling result in a solid-state material, Madhavan said.

The new massive electrons were measured topologically through scanning tunneling microscopy and electrically through spectroscopy, the researchers report.

The analysis revealed the Dirac point, which is the defining characteristic of the TCI, said Madhavan. Furthermore, the researchers found that varying the amount of tin imparted a measure of control over the material's properties, fulfilling yet another theoretical prediction.

Madhavan said the results confirmed the TCI's exotic band structure, a measure of the energy a surface electron may or may not possess within a solid. At the same time, the fundamental properties of the TCI remained accessible.

Moreover, observing and controlling Dirac electrons in TCIs paves the way for investigating relativistic physics in solid state systems: physics which was previously accessible only in the experiments of high-energy physics where particles are accelerated to speeds close to light.

In addition, the experiments revealed two distinct regimes of fermiology, an energy boundary used to make determinations about the properties of metals and semiconductors.


Story Source:

The above story is based on materials provided by Boston College. Note: Materials may be edited for content and length.


Journal Reference:

  1. Yoshinori Okada, Maksym Serbyn, Hsin Lin, Daniel Walkup, Wenwen Zhou, Chetan Dhital, Madhab Neupane, Suyang Xu, Yung Jui Wang, R. Sankar, Fangcheng Chou, Arun Bansil, M. Zahid Hasan, Stephen D. Wilson, Liang Fu, and Vidya Madhavan. Observation of Dirac Node Formation and Mass Acquisition in a Topological Crystalline Insulator. Science, 29 August 2013 DOI: 10.1126/science.1239451

Cite This Page:

Boston College. "Novel topological crystalline insulator shows mass appeal." ScienceDaily. ScienceDaily, 29 August 2013. <www.sciencedaily.com/releases/2013/08/130829145216.htm>.
Boston College. (2013, August 29). Novel topological crystalline insulator shows mass appeal. ScienceDaily. Retrieved September 17, 2014 from www.sciencedaily.com/releases/2013/08/130829145216.htm
Boston College. "Novel topological crystalline insulator shows mass appeal." ScienceDaily. www.sciencedaily.com/releases/2013/08/130829145216.htm (accessed September 17, 2014).

Share This



More Matter & Energy News

Wednesday, September 17, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Stocks Hit All-Time High as Fed Holds Steady

Stocks Hit All-Time High as Fed Holds Steady

AP (Sep. 17, 2014) The Federal Reserve signaled Wednesday that it plans to keep a key interest rate at a record low because a broad range of U.S. economic measures remain subpar. Stocks hit an all-time high on the news. (Sept. 17) Video provided by AP
Powered by NewsLook.com
Space Race Pits Bezos Vs Musk

Space Race Pits Bezos Vs Musk

Reuters - Business Video Online (Sep. 16, 2014) Amazon CEO Jeff Bezos' startup will team up with Boeing and Lockheed to develop rocket engines as Elon Musk races to have his rockets certified. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com
MIT's Robot Cheetah Unleashed — Can Now Run, Jump Freely

MIT's Robot Cheetah Unleashed — Can Now Run, Jump Freely

Newsy (Sep. 16, 2014) MIT developed a robot modeled after a cheetah. It can run up to speeds of 10 mph, though researchers estimate it will eventually reach 30 mph. Video provided by Newsy
Powered by NewsLook.com
Manufacturer Prints 3-D Car In Record Time

Manufacturer Prints 3-D Car In Record Time

Newsy (Sep. 15, 2014) Automobile manufacturer Local Motors created a drivable electric car using a 3-D printer. Printing the body only took 44 hours. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins