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.
  • 2018-02-02 08:00:00
  • Article ID: 688785

Scientists Discover 'Chiral Phonons' - Atomic Rotations in a 2-D Semiconductor Crystal

Experiments confirm the first chiral phonon that could enable exotic forms of electronics

  • Credit: Hanyu Zhu, et al.

    This diagram maps out atomic motion in separate phonon modes. At left ("LO" represents a longitudinal optical mode), selenium atoms exhibit a clockwise rotation while tungsten atoms stand still. At right ("LA" represents a longitudinal acoustic mode), tungsten atoms exhibit a clockwise rotation while selenium atoms rotate in a counterclockwise direction.

  • Credit: Hanyu Zhu, et al.

    The atomic motion in a 2-D material, tungsten disulfide, is shown in this animation. In this phonon mode (known as longitudinal optical mode or LO), the selenium atoms (yellow) rotate clockwise while the tungsten atoms (blue) are still.

A research team from the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) has found the first evidence that a shaking motion in the structure of an atomically thin (2-D) material possesses a naturally occurring circular rotation. 


This rotation could become the building block for a new form of information technology, and for the design of molecular-scale rotors to drive microscopic motors and machines.


The monolayer material, tungsten diselenide (WSe2), is already well-known for its unusual ability to sustain special electronic properties that are far more fleeting in other materials.


It is considered a promising candidate for a sought-after form of data storage known as valleytronics, for example, in which the momentum and wavelike motion of electrons in a material can be sorted into opposite “valleys” in a material’s electronic structure, with each of these valleys representing the ones and zeroes in conventional binary data.


Modern electronics typically rely on manipulations of the charge of electrons to carry and store information, though as electronics are increasingly miniaturized they are more subject to problems associated with heat buildup and electric leaks.


The latest study, published online Feb. 1 in the journal Science, provides a possible path to overcome these issues. It reports that some of the material’s phonons, a term describing collective vibrations in atomic crystals, are naturally rotating in a certain direction.


This property is known as chirality – similar to a person’s handedness where the left and right hand are a mirror image of each other but not identical. Controlling the direction of this rotation would provide a stable mechanism to carry and store information. 


“Phonons in solids are usually regarded as the collective linear motion of atoms,” said Xiang Zhang, the corresponding author of the study and senior scientist of the Materials Science Division at Lawrence Berkeley National Laboratory and professor at UC Berkeley. “Our experiment discovered a new type of so-called chiral phonons where atoms move in circles in an atomic monolayer crystal of tungsten diselenide.” 


Hanyu Zhu, the lead author of the study and a postdoctoral researcher at Zhang’s group, said, “One of the biggest advantage of chiral phonon is that the rotation is locked with the particle’s momentum and not easily disturbed.”


In the phonon mode studied, the selenium atoms appear to collectively rotate in a clockwise direction, while the tungsten atoms showed no motion. Researchers prepared a “sandwich” with four sheets of centimeter-sized monolayer WSe2 samples placed between thin sapphire crystals. They synced ultrafast lasers to record the time-dependent motions.


The two laser sources converged on a spot on the samples measuring just 70 millionths of a meter in diameter. One of the lasers was precisely switched between two different tuning modes to sense the difference of left and right chiral phonon activity. 


A so-called pump laser produced visible, red-light pulses that excited the samples, and a probe laser produced mid-infrared pulses that followed the first pump pulse within one trillionth of a second. About one mid-infrared photon in every 100 million is absorbed by WSe2 and converted to a chiral phonon. 


The researchers then captured the high-energy luminescence from the sample, a signature of this rare absorption event. Through this technique, known as transient infrared spectroscopy, researchers not only confirmed the existence of a chiral phonon but also accurately obtained its rotational frequency.


So far, the process only produces a small number of chiral phonons. A next step in the research will be to generate larger numbers of rotating phonons, and to learn whether vigorous agitations in the crystal can be used to flip the spin of electrons or to significantly alter the valley properties of the material. Spin is an inherent property of an electron that can be thought of as its compass needle – if it could be flipped to point either north or south it could be used to convey information in a new form of electronics called spintronics.


 “The potential phonon-based control of electrons and spins for device applications is very exciting and within reach,” Zhu said. “We already proved that phonons are capable of switching the electronic valley.  In addition, this work allows the possibility of using the rotating atoms as little magnets to guide the spin orientation.”


The chiral properties found in the study likely exist across a wide range of 2-D materials based on a similar patterning in their atomic structure, Zhu also noted, adding that the study could guide theoretical investigations of electron-phonon interactions and the design of materials to enhance phonon-based effects.


“The same principle works in all 2-D periodic structures with three-fold symmetry and inversion asymmetry” Zhu said. “The same principle covers a huge family of natural materials, and there are almost infinite possibilities for creating rotors at the molecular scale.”


Researchers at UC Berkeley, King Abdullah University of Science and Technology in Saudi Arabia, and Nanjing Normal University in China also participated in the study. This work was primarily supported by the U.S. Department of Energy’s Office of Science.




Lawrence Berkeley National Laboratory addresses the world’s most urgent scientific challenges by advancing sustainable energy, protecting human health, creating new materials, and revealing the origin and fate of the universe. Founded in 1931, Berkeley Lab’s scientific expertise has been recognized with 13 Nobel Prizes. The University of California manages Berkeley Lab for the U.S. Department of Energy’s Office of Science. For more, visit


DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit


  • Filters

  • × Clear Filters

The Relationship Between Charge Density Waves and Superconductivity? It's Complicated.

For a long time, physicists have tried to understand the relationship between a periodic pattern of conduction electrons called a charge density wave (CDW), and another quantum order, superconductivity, or zero electrical resistance, in the same material. Do they compete? Co-exist? Co-operate? Do they go their separate ways?

Splitting Water: Nanoscale Imaging Yields Key Insights

In the quest to realize artificial photosynthesis to convert sunlight, water, and carbon dioxide into fuel - just as plants do - researchers need to not only identify materials to efficiently perform photoelectrochemical water splitting, but also to understand why a certain material may or may not work. Now scientists at Lawrence Berkeley National Laboratory have pioneered a technique that uses nanoscale imaging to understand how local, nanoscale properties can affect a material's macroscopic performance.

Feeding Plants to This Algae Could Fuel Your Car

The research shows that a freshwater production strain of microalgae, Auxenochlorella protothecoides, is capable of directly degrading and utilizing non-food plant substrates, such as switchgrass, for improved cell growth and lipid productivity, useful for boosting the algae's potential value as a biofuel.

No More Zigzags: Scientists Uncover Mechanism That Stabilizes Fusion Plasmas

Article describes simulation of physics behind elimination of sawtooth instabilities.

Solutions to Water Challenges Reside at the Interface

Leading Argonne National Laboratory researcher Seth Darling describes the most advanced research innovations that could address global clean water accessibility.

New Cost-Effective Instrument Measures Molecular Dynamics on a Picosecond Timescale

Studying the photochemistry has shown that ultraviolet radiation can set off harmful chemical reactions in the human body and, alternatively, can provide "photo-protection" by dispersing extra energy. To better understand the dynamics of these photochemical processes, a group of scientists irradiated the RNA base uracil with ultraviolet light and documented its behavior on a picosecond timescale. They discuss their work this week in The Journal of Chemical Physics.

Exploding Waves from Colliding Dissipative Pulses

The interaction of traveling waves in dissipative systems, physical systems driven by energy dissipation, can yield unexpected and sometimes chaotic results. These waves, known as dissipative pulses are driving experimental studies in a variety of areas that involve matter and energy flows. In the journal Chaos, researchers discuss their work studying collisions between three types of DSs to determine what happens when these traveling waves interact.

Theorists Publish Highest-Precision Prediction of Muon Magnetic Anomaly

UPTON, NY--Theoretical physicists at the U.S. Department of Energy's (DOE's) Brookhaven National Laboratory and their collaborators have just released the most precise prediction of how subatomic particles called muons--heavy cousins of electrons--"wobble" off their path in a powerful magnetic field.

How Gold Nanoparticles Could Improve Solar Energy Storage

Star-shaped gold nanoparticles, coated with a semiconductor, can produce hydrogen from water over four times more efficiently than other methods - opening the door to improved storage of solar energy and other advances that could boost renewable energy use and combat climate change, according to Rutgers University-New Brunswick researchers.

National Ignition Facility Sets New Energy Record

Lawrence Livermore National Laboratory's National Ignition Facility (NIF) laser system has set a new record, firing 2.15 megajoules (MJ) of energy to its target chamber - a 15 percent improvement over NIF's design specification of 1.8 MJ, and more than 10 percent higher than the previous 1.9 MJ energy record set in March 2012. Increasing NIF's energy limit will expand the parameter space for stockpile stewardship experiments and provide a significant boost to the pursuit of ignition.

  • Filters

  • × Clear Filters

Funding for New DOE Energy Frontier Research Center at Brookhaven Lab

UPTON, NY--The U.S. Department of Energy (DOE) has announced funding for a new Energy Frontier Research Center (EFRC) to be led by DOE's Brookhaven National Laboratory. The Brookhaven EFRC, named "Molten Salts in Extreme Environments," will focus on understanding the properties of a class of materials with potential applications in energy technologies--particularly in nuclear power.

Two Stony Brook Researchers Receive Energy Frontier Research Center Awards Totaling $21.75M

Stony Brook University received notification from the U.S. Department of Energy (DOE) that two proposals directed by SBU faculty to expand or develop Energy Frontier Research Centers (EFRCs) designed to accelerate scientific breakthroughs needed to strengthen U.S. economic leadership and energy security will receive funding totaling $21.75 million. The two Stony Brook EFRCs are the Center for Mesoscale Transport Properties (m2M), led by renowned energy storage researcher, Esther Takeuchi, PhD, which will receive a four-year $12 million grant for the existing center; and the creation of a new EFRC, A Next Generation Synthesis Center (GENESIS) led by John Parise, PhD, which will receive a four-year $9.75 million grant.

Seth Davidovits Wins 2018 Marshall N. Rosenbluth Dissertation Award

Article describes dissertation award won by Seth Davidovits.

DOE Launches New Lab Partnering Service

The U.S. Department of Energy officially launched the Lab Partnering Service (LPS), an on-line, single access point platform for investors, innovators, and institutions to identify, locate, and obtain information from DOE's 17 national laboratories.

Department of Energy Announces $75 Million for High Energy Physics Research

The U.S. Department of Energy (DOE) announced $75 million in funding for 77 university research awards on a range of topics in high energy physics to advance knowledge of how the universe works at its most fundamental level.

Thesis Prize Winner's Calculations Characterize Neutrino Interactions

Alessandro Baroni is helping demystify one of the most mysterious particles. His work is contributing to our understanding of neutrinos, and it has earned him the 2017 Jefferson Science Associates Thesis Prize for work performed on a thesis related to research at the Department of Energy's Thomas Jefferson National Accelerator Facility

10 Questions for Steven Cowley, New Director of the Princeton Plasma Physics Laboratory

Steven Cowley, a theoretical physicist and international authority on fusion energy, became the seventh Director of the Princeton Plasma Physics Laboratory (PPon July 1 and will be Princeton professor of astrophysical sciences on September 1.

Ames Laboratory to lead new Center for Advancement of Topological Semimetals

Ames Laboratory will receive $10.75 million over four yearrs for a new Center for Advancement of Topological Semimetals as one of the Department of Energy's Energy Frontier Research Centers.

DOE Awards $100 Million for Energy Frontier Research Centers

U.S. Secretary of Energy Rick Perry announced $100 million in funding for 42 Energy Frontier Research Centers (EFRCs) to accelerate the scientific breakthroughs needed to strengthen U.S. economic leadership and energy security.

Argonne welcomes <em>The Martian</em> author Andy Weir

Best-selling science fiction author Andy Weir visited Argonne to give a series of standing-room-only talks, inspiring students and scientists alike.

  • Filters

  • × Clear Filters

Sugar-Coated Sheets Selectively Target Pathogens

Researchers design self-assembling nanosheets that mimic the surface of cells.

Tracking Down Helium-4's Quarks and Gluons

Scientists obtain the first exclusive measurement of deeply virtual Compton scattering of electrons off helium-4, vital to obtaining an unambiguous 3-D view of quarks and gluons within nuclei.

Predicting Magnetic Explosions: From Plasma Current Sheet Disruption to Fast Magnetic Reconnection

Supercomputer simulations and theoretical analysis shed new light on when and how fast reconnection occurs.

Is Nature Exclusively Left Handed? Using Chilled Atoms to Find Out

Elegant techniques of trapping and polarizing atoms open vistas for beta-decay tests of fundamental symmetries, key to understanding the most basic forces and particles constituting our universe.

As Future Batteries, Hybrid Supercapacitors Are Super-Charged

A new supercapacitor could be a competitive alternative to lithium-ion batteries.

Forever Young Catalyst Reduces Diesel Emissions

Atom probe tomography reveals key explanations for stable performance over a cutting-edge diesel-exhaust catalyst's lifetime.

Sense Like a Shark: Saltwater-Submersible Films

A nickelate thin film senses electric field changes analogous to the electroreception sensing organ in sharks, which detects the bioelectric fields of prey.

A Bit of Quantum Logic--What Did the Atom Say to the Quantum Dot?

Let's talk! Scientists demonstrate coherent coupling between a quantum dot and a donor atom in silicon, vital for moving information inside quantum computers.

New Tech Uses Isomeric Beams to Study How and Where the Galaxy Makes One of Its Most Common Elements

A new measurement using a beam of aluminum-26 prepared in a metastable state allows researchers to better understand the creation of the elements in our galaxy.

Simulations of Magnetically Confined Plasmas Reveal a Self-Regulating Stabilizing Mechanism

A mysterious mechanism that prevents instabilities may be similar to the process that maintains the Earth's magnetic field.


Tuesday July 03, 2018, 11:05 AM

2018 RHIC & AGS Annual Users' Meeting: 'Illuminating the QCD Landscape'

Brookhaven National Laboratory

Friday June 29, 2018, 06:05 PM

Argonne welcomes The Martian author Andy Weir

Argonne National Laboratory

Monday June 18, 2018, 09:55 AM

Creating STEM Knowledge and Innovations to Solve Global Issues Like Water, Food, and Energy

Illinois Mathematics and Science Academy (IMSA)

Friday June 15, 2018, 10:00 AM

Professor Emily Liu Receives $1.8 Million DoE Award for Solar Power Systems Research

Rensselaer Polytechnic Institute (RPI)

Thursday June 07, 2018, 03:05 PM

Celebrating 40 years of empowerment in science

Argonne National Laboratory

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

Showing results

0-4 Of 2215