Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > Interdisciplinary team demonstrates superconducting qualities of topological insulators: Findings may prove useful in search for elusive Majorana quasiparticle

Top left: SEM image of a typical device. Mechanically exfoliated Bi2Se3 thin film is colored as brown and contact metals consist of Ti(2.5nm)/Al(140nm). Top right: Hall data where red curve is longitudinal resistivity and blue curve is Hall carrier density as a function of gate voltage. Bottom figure: 2D plot of differential resistance as a function of gate voltage(x axis) and current(y axis). Purple region in the center corresponds to zero differential resistance (superconducting regime)
Credit: Sungjae Cho, Department of Physics & Frederick Seitz Materials Research Laboratory
Top left: SEM image of a typical device. Mechanically exfoliated Bi2Se3 thin film is colored as brown and contact metals consist of Ti(2.5nm)/Al(140nm). Top right: Hall data where red curve is longitudinal resistivity and blue curve is Hall carrier density as a function of gate voltage. Bottom figure: 2D plot of differential resistance as a function of gate voltage(x axis) and current(y axis). Purple region in the center corresponds to zero differential resistance (superconducting regime)

Credit: Sungjae Cho, Department of Physics & Frederick Seitz Materials Research Laboratory

Abstract:
Topological insulators (TIs) are an exciting new type of material that on their surface carry electric current, but within their bulk, act as insulators. Since the discovery of TIs about a decade ago, their unique characteristics (which point to potential applications in quantum computing) have been explored theoretically, and in the last five years, experimentally.

Interdisciplinary team demonstrates superconducting qualities of topological insulators: Findings may prove useful in search for elusive Majorana quasiparticle

Urbana, IL | Posted on April 10th, 2013



But where in theory, the bulk of TIs carry no current, in the laboratory, impurities and disorder in real materials mean that the bulk is, in fact, conductive. This has proven an obstacle to experimentation with TIs: findings from prior experiments designed to test the surface conductivity of TIs unavoidably included contributions from the surplus of electrons in the bulk.

Now an interdisciplinary research team at the University of Illinois at Urbana-Champaign, in collaboration with researchers at Brookhaven National Laboratory's Condensed Matter Physics and Materials Science Department, has measured superconductive surface states in TIs where the bulk charge carriers were successfully depleted. The research paper, "Symmetry protected Josephson supercurrents in three-dimensional topological insulators," was published this week in Nature Communications.

The experiments, conducted in the laboratory of Illinois condensed matter physicist Nadya Mason at the Frederick Seitz Materials Research Laboratory, were carried out by postdoctoral research associate Sungjae Cho using TI material—specially developed by the Brookhaven team—coupled to superconducting leads.

To deplete the electrons in the bulk, the team used three strategies: the TI material was doped with antimony, then it was doped at the surface with a chemical with strong electron affinity, and finally an electrostatic gate was used to apply voltage that lowered the energy of the entire system.

"One of the main results we found," said Mason, "was in comparing the two experimental regimes, pure surface (bulk depleted of electrons) vs. bulk (excess electrons present in impurities in bulk material). We learned that even when you have the bulk, the superconductivity always goes through the surface of the material."

This finding was established by comparing experiments with theoretical modeling by research team members at Illinois's Department of Electrical and Computer Engineering—Assistant Professor Matthew Gilbert and graduate student Brian Dellabetta—which showed that superconductivity occured only at the surface of topological insulators and that this is a unique characteristic of these new materials.

It's been predicted that TIs harbor the highly sought Majorana quasiparticle, a fermion which is theorized to be its own antiparticle and which if discovered, could serve as a quantum bit in quantum computing.

"Since we now have a better understanding of how topological insulators behave with regard to superconductivity, this will assist our search for the Majorana quasiparticle," Mason explained.

The team also plans to investigate the same experimental configuration at lower energy to further explore its characteristics.

"The potential of this new material is very exciting. We are exploring possible uses for TIs in terms of conventional electronic devices and novel devices," said Mason. "And if we can find the new particle predicted to exist in the material's solid state, and then learn to manipulate its position relative to a second particle, we could use it for quantum computation.

"The implications for quantum computing are truly profound," she explained. "With today's technology, computer components really can't get much smaller. If Majoranas behave as predicted and can be manipulated to serve as quantum bits, our future computers would be extraordinarily powerful; their components would be much smaller and would be able to store much more information."

This research was funded by a grant from the Office of Naval Research under grant N0014-11-1-0728.

####

For more information, please click here

Contacts:
Nadya Mason

217-244-9114

Writer:
Siv Schwink
Department of Physics
217/552-5671

Copyright © University of Illinois College of Engineering

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

Non-Enzyme Sensor Determines Level of Blood Sugar July 29th, 2015

Flexible Future of Point-of-Care Disease Diagnostic July 29th, 2015

Meet the high-performance single-molecule diode: Major milestone in molecular electronics scored by Berkeley Lab and Columbia University team July 29th, 2015

Detecting small metallic contaminants in food via magnetization: A practical metallic-contaminant detecting system using three high-Tc RF superconducting quantum interference devices (SQUIDs) July 29th, 2015

Controlling phase changes in solids: Controlling phase changes in solids July 29th, 2015

Physics

Meet the high-performance single-molecule diode: Major milestone in molecular electronics scored by Berkeley Lab and Columbia University team July 29th, 2015

Detecting small metallic contaminants in food via magnetization: A practical metallic-contaminant detecting system using three high-Tc RF superconducting quantum interference devices (SQUIDs) July 29th, 2015

Superconductivity

Detecting small metallic contaminants in food via magnetization: A practical metallic-contaminant detecting system using three high-Tc RF superconducting quantum interference devices (SQUIDs) July 29th, 2015

Govt.-Legislation/Regulation/Funding/Policy

Meet the high-performance single-molecule diode: Major milestone in molecular electronics scored by Berkeley Lab and Columbia University team July 29th, 2015

New computer model could explain how simple molecules took first step toward life: Two Brookhaven researchers developed theoretical model to explain the origins of self-replicating molecules July 28th, 2015

Short wavelength plasmons observed in nanotubes: Berkeley Lab researchers create Ludinger liquid plasmons in metallic SWNTs July 28th, 2015

Smart hydrogel coating creates 'stick-slip' control of capillary action July 27th, 2015

Chip Technology

March 2016; 6th Int'l Conference on Nanostructures in Iran July 29th, 2015

Meet the high-performance single-molecule diode: Major milestone in molecular electronics scored by Berkeley Lab and Columbia University team July 29th, 2015

Nanometrics Announces Upcoming Investor Events July 28th, 2015

Short wavelength plasmons observed in nanotubes: Berkeley Lab researchers create Ludinger liquid plasmons in metallic SWNTs July 28th, 2015

Quantum Computing

Quantum networks: Back and forth are not equal distances! July 28th, 2015

The quantum middle man July 2nd, 2015

Freezing single atoms to absolute zero with microwaves brings quantum technology closer: Atoms frozen to absolute zero using microwaves July 2nd, 2015

Producing spin-entangled electrons July 2nd, 2015

Discoveries

Non-Enzyme Sensor Determines Level of Blood Sugar July 29th, 2015

Flexible Future of Point-of-Care Disease Diagnostic July 29th, 2015

Meet the high-performance single-molecule diode: Major milestone in molecular electronics scored by Berkeley Lab and Columbia University team July 29th, 2015

Detecting small metallic contaminants in food via magnetization: A practical metallic-contaminant detecting system using three high-Tc RF superconducting quantum interference devices (SQUIDs) July 29th, 2015

Announcements

Non-Enzyme Sensor Determines Level of Blood Sugar July 29th, 2015

Flexible Future of Point-of-Care Disease Diagnostic July 29th, 2015

Meet the high-performance single-molecule diode: Major milestone in molecular electronics scored by Berkeley Lab and Columbia University team July 29th, 2015

Detecting small metallic contaminants in food via magnetization: A practical metallic-contaminant detecting system using three high-Tc RF superconducting quantum interference devices (SQUIDs) July 29th, 2015

Military

Smart hydrogel coating creates 'stick-slip' control of capillary action July 27th, 2015

Researchers predict material with record-setting melting point July 27th, 2015

Reshaping the solar spectrum to turn light to electricity: UC Riverside researchers find a way to use the infrared region of the sun's spectrum to make solar cells more efficient July 27th, 2015

Superfast fluorescence sets new speed record: Plasmonic device has speed and efficiency to serve optical computers July 27th, 2015

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