Doe Science news source
The DOE Science News Source is a Newswise initiative to promote research news from the Office of Science of the DOE to the public and news media.
  • 2018-01-09 11:05:51
  • Article ID: 687670

An Exotic State of Matter Discovered in 2-D Material

Electrons are forced to the edge of the road on a thin sheet of tungsten ditelluride.

  • Credit: Image courtesy of David Cobden

    An exotic state of matter called a topological insulator has been observed in 3-D materials and artificial nanostructures, but not in simple 2-D materials—until now. The sketch shows a transistor made of a single layer of tungsten ditelluride, platinum electrical contacts (gray bars), and an insulating material (blue) that provides air-tight encapsulation. Voltage is applied to the graphene sheets (dark grey) on the top and bottom to control the sheet conductivity. When the conductivity is very low, the current between the contacts flows only at the edge of the 2-D material—as expected for a 2-D topological insulator!

The Science

After flaking a single layer of tungsten ditelluride off a larger crystal, scientists used it in a specially designed transistor. The transistor allowed electrical transport measurements. In the experiments, electrical current moved only at the edges. This is the first realization of controlled, edge-restricted conduction in this new class of ultrathin materials. The edge conductivity was good in spite of the roughness at the torn edges of the flake.

The Impact

This is the first of a new family of materials that can be used to explore the physics of topological insulators. These insulators are an odd state of matter. The material’s interior doesn’t conduct electrons, but the edges do. It opens the door to tailoring topological electronic properties by stacking different thin sheets, or 2-D materials. These exotic 2-D materials could be used as a platform for energy-efficient computing (spintronics) and to solve today’s intractable challenges with quantum computing.

Summary

Like graphene, the semi-metal tungsten ditelluride (WTe2) can be prepared in a single monolayer. Tellurium atoms sandwich the transition metal tungsten in each layer. These sandwiched transition metal materials are important for future electronics and photonics. Scientists have predicted that WTe2 in monolayer form has the exotic electronic properties of the class of materials known as topological insulators. However, the surface of WTe2 oxidizes in air, destroying the electronic properties. Now, researchers have made devices from WTe2, down to a single layer thick, that are air-stable and have good electrical contacts. Surprisingly, the team found that in the case of a single layer, the sheet became insulating at liquid nitrogen temperatures when no gate voltage was applied. For large enough positive or negative contact voltages, the electrical current switched on, as in a transistor. Most remarkably though, the insulating state is not fully insulating—it still conducts at the edges. Multi-contact electrical transport measurements and scanning probe techniques verified this conductivity at the edge. This edge conduction is just what is expected for a 2-D topological insulator. It exhibits another topological signature in its electronic spectrum: electron states at all energies, without a gap normally found in semiconductors and insulators. The special edge conductivity is sensitive to a magnetic field pointing parallel to the layer. These observations are consistent with the edge conduction channels behaving like quantum mechanical wires in which the electron magnetic direction, known as spin, is locked to the direction of electron travel. The edge of the material can, therefore, be used to filter electrons by spin direction. The only previous 2-D topological insulator candidates were quantum wells in sophisticated semiconductor heterostructures. Likewise, this 2-D material can readily be combined with layers of superconducting and magnetic materials. It may thus provide the basis of a platform for spin-based or topologically protected quantum computing.

Funding

The major part of this work was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences. Some co-authors were supported by the Air Force Office of Scientific Research and the National Science Foundation. Materials were provided by Oak Ridge National Laboratory.

Publication

Z. Fei, T. Palomaki, S. Wu, W. Zhao, X. Cai, B. Sun, P. Nguyen, J. Finney, X. Xu, and D.H. Cobden, "Edge conduction in monolayer WTe2." Nature Physics 13, 677-682 (2017). [DOI: 10.1038/nphys4091]

Read more highlights from the DOE Office of Science at https://science.energy.gov/news/highlights/

X
X
X
  • Filters

  • × Clear Filters

Powering Up With a Smart Window

Window material repeatedly switches from being see-through to blocking the heat and converting sunlight into electricity.

Remnant Superconductivity From Invisible Stripes

Scientists used an intense light to unveil hidden rivers that transport electricity with no loss.

Columbia Researchers Squeeze Light into Nanoscale Devices and Circuits

Columbia investigators have made a major breakthrough in nanophotonics research, with their invention of a novel "home-built" cryogenic near-field optical microscope that has enabled them to directly image, for the first time, the propagation and dynamics of graphene plasmons at variable temperatures down to negative 250 degrees Celsius. If researchers can harness this nanolight, they will be able to improve sensing, subwavelength waveguiding, and optical transmission of signals.

Self-Assembling 3D Battery Would Charge in Seconds

A cross-campus collaboration led by Ulrich Wiesner, professor of engineering at Cornell University, has resulted in a novel energy storage device architecture that has the potential for lightning-quick charges for electronic devices.

Understanding the Generation of Light-Induced Electrical Current in Atomically Thin Nanomaterials

Scientists added an imaging capability to Brookhaven Lab's Center for Functional Nanomaterials that could provide the optoelectronic information needed to improve the performance of devices for power generation, communications, data storage, and lighting.

Diamond 'Spin-Off' Tech Could Lead to Low-Cost Medical Imaging and Drug Discovery Tools

An international team led by scientists at Berkeley Lab and UC Berkeley discovered how to exploit defects in nanoscale and microscale diamonds and potentially enhance the sensitivity of magnetic resonance imaging and nuclear magnetic resonance systems while eliminating the need for their costly and bulky superconducting magnets.

PROSPECTing For Antineutrinos

The Precision Reactor Oscillation and Spectrum Experiment (PROSPECT) has completed installation of a novel antineutrino detector that will probe the possible existence of a new form of matter - sterile neutrinos.

How to Cope with Cases of Mistaken Identity: MINERvA's Tale of Pions and Neutrinos

Neutral pion production is a major character in a story of mistaken identity worthy of an Agatha Christie novel.

Perfecting the Noise-Canceling Neutrino Detector

MicroBooNE neutrino experiment cuts through the noise, clearing the way for signals made by the hard-to-detect particle.

Supersonic Waves May Help Electronics Beat the Heat

Researchers at the Department of Energy's Oak Ridge National Laboratory made the first observations of waves of atomic rearrangements, known as phasons, propagating supersonically through a vibrating crystal lattice--a discovery that may dramatically improve heat transport in insulators and enable new strategies for heat management in future electronics devices.


  • Filters

  • × Clear Filters

Power to the People

The University of Utah College of Engineering has received a $2 million grant to create a laboratory and develop new technology for communities with backup power sources, known as microgrids, so they can quickly and more securely operate in the event of a massive power outage due to a natural disaster or cyberattack.

The U. S. Department of Energy Announces $34 Million for Small Business Research and Development Grants

U.S. Energy Secretary Rick Perry announced that the Department of Energy will award 219 grants totaling $34 million to 183 small businesses in 41 states. Funded through DOE's Small Business Innovation Research (SBIR) and Small Business Technology Transfer (STTR) programs, today's selections are for Phase I research and development.

Raising the Heat to Lower the Cost of Solar Energy

Sandia National Laboratories will receive $10.5 million from the Department of Energy to research and design a cheaper and more efficient solar energy system.The work focuses on refining a specific type of utility-scale solar energy technology that uses mirrors to reflect and concentrate sunlight onto a receiver on a tower.

Solar Turbines, Inc. Selects Penn State to Establish Center of Excellence in Gas Turbines

After completing an extensive evaluation of institutions of higher learning in the United States and Europe, Solar Turbines Incorporated has chosen Penn State as a university partner to establish a center of excellence in gas turbines. The center involves numerous faculty across Penn State's College of Engineering.

ORNL Facility Receives American Nuclear Society's Historic Landmark Designation

The American Nuclear Society has designated the Radiochemical Engineering Development Center at the Department of Energy's Oak Ridge National Laboratory an ANS Nuclear Historic Landmark, recognizing more than 50 years of isotope production and nuclear fuel cycle research.

Steven Cowley named director of DOE's Princeton Plasma Physics Laboratory

Steven Cowley, a theoretical physicist and international authority on fusion energy, has been named director of the U.S. Department of Energy's (DOE) Princeton Plasma Physics Laboratory (PPPL), effective July 1.

Scientists Turn X-ray Laser Into World's Fastest Water Heater

Scientists have used a powerful X-ray laser at the Department of Energy's SLAC National Accelerator Laboratory to heat water from room temperature to 100,000 degrees Celsius in less than a tenth of a picosecond, or millionth of a millionth of a second.

PNNL Part of a New National Center for Near-Atomic Resolution of Biological Molecules

A collaboration between the Pacific Northwest National Laboratory and Oregon Health & Science University has been chosen as a national center for a Nobel Prize-winning method of imaging, cryo-electron microscopy, that is revolutionizing structural biology.

SLAC Will Open One of Three NIH National Service Centers for Cryo-Electron Microscopy

The National Institutes of Health announced today that it will establish a national service and training center for cryogenic electron microscopy research at the Department of Energy's SLAC National Accelerator Laboratory.

Planck Collaboration Wins 2018 Gruber Cosmology Prize

The Planck Team--including researchers in Lawrence Berkeley National Laboratory's (Berkeley Lab's) Computational Research and Physics divisions--have been awarded the 2018 Gruber Cosmology Prize.


  • Filters

  • × Clear Filters

Powering Up With a Smart Window

Window material repeatedly switches from being see-through to blocking the heat and converting sunlight into electricity.

Remnant Superconductivity From Invisible Stripes

Scientists used an intense light to unveil hidden rivers that transport electricity with no loss.

Cracking the Code of Superconductivity and Magnetism

Neutron probes and theory reveal how electrons cooperate at lower temperatures.

The Secret to Measuring an Antineutrino's Energy

Scientists are developing better models that describe both neutrino and antineutrino data, which can offer insights into the nature of the universe.

How to Cope with Cases of Mistaken Identity: MINERvA's Tale of Pions and Neutrinos

Neutral pion production is a major character in a story of mistaken identity worthy of an Agatha Christie novel.

Perfecting the Noise-Canceling Neutrino Detector

MicroBooNE neutrino experiment cuts through the noise, clearing the way for signals made by the hard-to-detect particle.

Keeping Tabs on Polysulfides in Batteries

Optimizing lithium-sulfur battery electrolytes for long life.

Huge "Thermometer" Takes Temperatures of Tiny Samples

New spectroscopic technique measures heat in itty-bitty volumes that could reveal insights for electronics and energy technology.

Water, Water, Everywhere, but How Does It Flow?

Scientists use new X-ray technique to see how water moves at the molecular level.

Magnetized Plasmas That "Twist Light" Can Produce Powerful Microscopes and More

A non-twisting laser beam moving through magnetized plasma turns into an optical vortex that traps, rotates, and controls microscopic particles, opening new frontiers in imaging.


Spotlight

Monday May 07, 2018, 10:30 AM

Introducing Graduate Students Across the Globe to Photon Science

Brookhaven National Laboratory

Wednesday May 02, 2018, 04:05 PM

Students from Massachusetts and Washington Win DOE's 28th National Science Bowl(r)

Department of Energy, Office of Science

Thursday April 12, 2018, 07:05 PM

The Race for Young Scientific Minds

Argonne National Laboratory

Wednesday March 14, 2018, 02:05 PM

Q&A: Al Ashley Reflects on His Efforts to Diversify SLAC and Beyond

SLAC National Accelerator Laboratory

Thursday February 15, 2018, 12:05 PM

Insights on Innovation in Energy, Humanitarian Aid Highlight UVA Darden's Net Impact Week

University of Virginia Darden School of Business

Friday February 09, 2018, 11:05 AM

Ivy League Graduate, Writer and Activist with Dyslexia Visits CSUCI to Reframe the Concept of Learning Disabilities

California State University, Channel Islands

Wednesday January 17, 2018, 12:05 PM

Photographer Adam Nadel Selected as Fermilab's New Artist-in-Residence for 2018

Fermi National Accelerator Laboratory (Fermilab)

Wednesday January 17, 2018, 12:05 PM

Fermilab Computing Partners with Argonne, Local Schools for Hour of Code

Fermi National Accelerator Laboratory (Fermilab)

Wednesday December 20, 2017, 01:05 PM

Q&A: Sam Webb Teaches X-Ray Science from a Remote Classroom

SLAC National Accelerator Laboratory

Monday December 18, 2017, 01:05 PM

The Future of Today's Electric Power Systems

Rensselaer Polytechnic Institute (RPI)

Monday December 18, 2017, 12:05 PM

Supporting the Development of Offshore Wind Power Plants

Rensselaer Polytechnic Institute (RPI)

Tuesday October 03, 2017, 01:05 PM

Stairway to Science

Argonne National Laboratory

Thursday September 28, 2017, 12:05 PM

After-School Energy Rush

Argonne National Laboratory

Thursday September 28, 2017, 10:05 AM

Bringing Diversity Into Computational Science Through Student Outreach

Brookhaven National Laboratory

Thursday September 21, 2017, 03:05 PM

From Science to Finance: SLAC Summer Interns Forge New Paths in STEM

SLAC National Accelerator Laboratory

Thursday September 07, 2017, 02:05 PM

Students Discuss 'Cosmic Opportunities' at 45th Annual SLAC Summer Institute

SLAC National Accelerator Laboratory

Thursday August 31, 2017, 05:05 PM

Binghamton University Opens $70 Million Smart Energy Building

Binghamton University, State University of New York

Wednesday August 23, 2017, 05:05 PM

Widening Horizons for High Schoolers with Code

Argonne National Laboratory

Saturday May 20, 2017, 12:05 PM

Rensselaer Polytechnic Institute Graduates Urged to Embrace Change at 211th Commencement

Rensselaer Polytechnic Institute (RPI)

Monday May 15, 2017, 01:05 PM

ORNL, University of Tennessee Launch New Doctoral Program in Data Science

Oak Ridge National Laboratory

Friday April 07, 2017, 11:05 AM

Champions in Science: Profile of Jonathan Kirzner

Department of Energy, Office of Science

Wednesday April 05, 2017, 12:05 PM

High-Schooler Solves College-Level Security Puzzle From Argonne, Sparks Interest in Career

Argonne National Laboratory

Tuesday March 28, 2017, 12:05 PM

Champions in Science: Profile of Jenica Jacobi

Department of Energy, Office of Science

Friday March 24, 2017, 10:40 AM

Great Neck South High School Wins Regional Science Bowl at Brookhaven Lab

Brookhaven National Laboratory

Wednesday February 15, 2017, 04:05 PM

Middle Schoolers Test Their Knowledge at Science Bowl Competition

Argonne National Laboratory

Friday January 27, 2017, 04:00 PM

Haslam Visits ORNL to Highlight State's Role in Discovering Tennessine

Oak Ridge National Laboratory

Tuesday November 08, 2016, 12:05 PM

Internship Program Helps Foster Development of Future Nuclear Scientists

Oak Ridge National Laboratory

Friday May 13, 2016, 04:05 PM

More Than 12,000 Explore Jefferson Lab During April 30 Open House

Thomas Jefferson National Accelerator Facility

Monday April 25, 2016, 05:05 PM

Giving Back to National Science Bowl

Ames Laboratory

Friday March 25, 2016, 12:05 PM

NMSU Undergrad Tackles 3D Particle Scattering Animations After Receiving JSA Research Assistantship

Thomas Jefferson National Accelerator Facility

Tuesday February 02, 2016, 10:05 AM

Shannon Greco: A Self-Described "STEM Education Zealot"

Princeton Plasma Physics Laboratory

Monday November 16, 2015, 04:05 PM

Rare Earths for Life: An 85th Birthday Visit with Mr. Rare Earth

Ames Laboratory

Tuesday October 20, 2015, 01:05 PM

Meet Robert Palomino: 'Give Everything a Shot!'

Brookhaven National Laboratory

Tuesday April 22, 2014, 11:30 AM

University of Utah Makes Solar Accessible

University of Utah

Wednesday March 06, 2013, 03:40 PM

Student Innovator at Rensselaer Polytechnic Institute Seeks Brighter, Smarter, and More Efficient LEDs

Rensselaer Polytechnic Institute (RPI)

Friday November 16, 2012, 10:00 AM

Texas Tech Energy Commerce Students, Community Light up Tent City

Texas Tech University

Wednesday November 23, 2011, 10:45 AM

Don't Get 'Frosted' Over Heating Your Home This Winter

Temple University

Wednesday July 06, 2011, 06:00 PM

New Research Center To Tackle Critical Challenges Related to Aircraft Design, Wind Energy, Smart Buildings

Rensselaer Polytechnic Institute (RPI)

Friday April 22, 2011, 09:00 AM

First Polymer Solar-Thermal Device Heats Home, Saves Money

Wake Forest University

Friday April 15, 2011, 12:25 PM

Like Superman, American University Will Get Its Energy from the Sun

American University

Thursday February 10, 2011, 05:00 PM

ARRA Grant to Help Fund Seminary Building Green Roof

University of Chicago

Tuesday December 07, 2010, 05:00 PM

UC San Diego Installing 2.8 Megawatt Fuel Cell to Anchor Energy Innovation Park

University of California San Diego

Monday November 01, 2010, 12:50 PM

Rensselaer Smart Lighting Engineering Research Center Announces First Deployment of New Technology on Campus

Rensselaer Polytechnic Institute (RPI)

Friday September 10, 2010, 12:40 PM

Ithaca College Will Host Regional Clean Energy Summit

Ithaca College

Tuesday July 27, 2010, 10:30 AM

Texas Governor Announces $8.4 Million Award to Create Renewable Energy Institute

Texas Tech University

Friday May 07, 2010, 04:20 PM

Creighton University to Offer New Alternative Energy Program

Creighton University

Wednesday May 05, 2010, 09:30 AM

National Engineering Program Seeks Subject Matter Experts in Energy

JETS Junior Engineering Technical Society

Wednesday April 21, 2010, 12:30 PM

Students Using Solar Power To Create Sustainable Solutions for Haiti, Peru

Rensselaer Polytechnic Institute (RPI)





Showing results

0-4 Of 2215