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.
  • 2018-06-07 12:05:23
  • Article ID: 695768

Hidden Magnetism Appears under Hidden Symmetry

  • (Image Credit: Brookhaven National Laboratory. Artistic rendering of a pair of antiferromagnetically coupled spins driven by magnetic field through the hidden symmetry.)

  • UT Physics researchers Jian Liu (assistant professor), Lin Hao (postdoc), Clayton Frederick (graduate student), and Junyi Yang (graduate student). To the right are Cristian Bastista (top, Lincoln Chair and professor), and Hidemaro Suwa (postdoc).

Sometimes a good theory just needs to right materials to make it work. That’s the case with recent findings by UT’s physicists and their colleagues, who designed a two-dimensional magnetic system that points to the possibility of devices with increased security and efficiency, using only a small amount of energy. By exploiting a hidden symmetry in the material, their results support a theory first proposed 20 years ago.

Keeping Control without Losing Flexibility

People have known about magnetism since ancient times but are still learning how it works, especially at the quantum scale. In ferromagnets, atoms and their neighbors have magnetic moments (caused by spin) that all align along the same direction. We can easily control that direction by an external magnetic field. In antiferromagnets, however, the magnetic moments anti-align with their neighbors and alternate one-by-one. This microscopic spin alignment perfectly shields any external magnetic field and is hidden from the outside world. Antiferromagnets were discovered by Louis Néel in 1948, but were described in his 1970 Nobel lecture as being theoretically interesting but technologically useless.

Jian Liu, assistant professor of physics, explained that generally spins in an antiferromagnet can rotate anyway they want as long as the anti-alignment is maintained. But, if the interaction between the atoms is anistropic, “it will give the spin a certain preferential direction.” This is the DM (Dzyaloshinskii-Moriya) interaction originating from relativistic effect, and Liu explained that it does two things. First, it tilts (or cants) the spins slightly away from the perfect anti-alignment, which is good because this means that an external magnetic field won’t be completely shielded and can couple to the canted spins, even if they’re staggered. There’s a tradeoff, however, in that while this interaction allows for canting, it pins the direction.

"So you are gaining some control," Liu said, "but you’re also losing some flexibility. And that evens out."

To get around this problem, he and a team of fellow researchers exploited a hidden spin symmetry: SU(2).

"SU(2) is actually a terminology that theorists and mathematicians use in group theory," Liu said. "What it means is that spin is isotropic—it can point in any direction that you want."

Yet how, exactly, is this symmetry hidden?

Liu said it’s hiding if you only look at things from a local scale.

"For example, if you sit at one spin, and you look around, you see a very anisotropic environment," he explained. "Basically, the other spins—your neighbors—are telling you that you have to cant (a certain way) to be compatible with them. If you look at a very global scale—if you consider all the spins—it turns out the entire system is perfectly isotropic and preserves this rotational symmetry.

"You can think of it this way," he continued, "hundreds years ago, people thought the earth was flat. That’s because we were sitting at a very local scale. We thought that if we continue to walk along one direction we would never come back to the same point. But it turns out the earth is a sphere, so if you continue walking north at some point you pass the pole and then you come back. So if you look at the earth on a global scale, you see that it has rotational symmetry, which you would not notice if you’re bound to the surface."

Adding Just Enough Space

The role of this global symmetry in antiferromagnetic systems was actually predicted two decades ago. Liu said while the theory was fascinating, the material used to test it wasn’t suitable for the task.

For their studies, he and his colleagues grew samples made from strontium, iridium, and oxygen (SrIrO3), as well as strontium, titanium, and oxygen (SrTiO3) and, using pulsed laser deposition, grew them on a base layer of SrTiO3 only a single crystal thick. They focused on three points: the material’s chemistry, preservation of the symmetry, and a crucial additional layer. Iridium proved to be an important choice because it provided strong DM interaction. The structure enables the hidden symmetry, largely because the team separated the layers with a “spacer” of SrTiO3 so that each layer would have its own two-dimensional properties.

The inspiration for this research came last year after Liu and fellow scientists published results on controlling ultrafine materials in Physical Review Letters. He explained that once they found a way to separate the layers to explore intrinsic two-dimensional properties, they realized they had a material that could test the symmetry theory.

Safer Systems; Faster Switching

Aside from scientific discovery, these latest research findings also present the potential to control antiferromagnetism for more secure and efficient devices.

As Liu explained, most current magnetic devices are based on ferromagnetic materials.

"However, we are getting to the limit of the performance of ferromagnets," he said. "We need to find another way to overcome the technical barrier. Antiferromagnetism provides another option. For example, antiferromagnetic materials have this anti-aligned spin. So if you look at an antiferromagnet, there’s no magnetic field around it. It actually appears to you as no different from a material that’s not magnetic, because they fully compensate each other."

What that means, he continued, is that we don’t want the bits in our computer hard drive to get too close to each other because each bit is one ferromagnet. This limits the density of the information storage.

"Now if the bits are antiferromagnetic, they will be magnetically invisible to each other, and you can pack them right next to each other," he said. "Essentially the storage capacity will dramatically increase."

Another possible benefit is more efficient switching in devices.

Liu said that switching the spins up and down in ferromagnetics is a slow and energy-costly process because we have to turn around its magnetic field on a macroscopic scale. With the anti-aligned spins in antiferromagnets under the hidden symmetry, he said, "it displays no magnetic field, and we just need to apply a little bit of energy to turn it on and off or rotate it. The amount of energy that we put into the system is very tiny compared to the self-anti-alignment energy, but the spins still respond instantaneously, and that makes the switching process much faster."

The Importance of Collaboration and Investment

The initial results were very encouraging, yet the experimental team wanted some additional verification.

"At the very beginning we couldn’t believe what we saw because the effects were really strong and the amount of energy you put into the system is one-thousandth of (its) internal energy," he explained. "It almost sounds too good to be true."

For validation, they took their questions to UT Physics Professor (and Lincoln Chair) Cristian Batista, a theorist in condensed matter physics.

"He guided us through all the detail of the theory and he came up with the explanation: not just qualitatively but actually quantitatively," Liu said. "He did the simulation and found that everything perfectly fell into the requirements for that theory of hidden symmetry."

In this case, collaboration—not only between experimentalists and theorists—proved to be an important element of success. The results were published in Nature Physics and the co-authors include faculty, postdocs, and students from UT Physics (Liu, Batista, Lin Hao, Hidemaro Suwa, Junyi Yang, and Clayton Frederick) as well as UT Materials Science and Engineering. Scientists from Brookhaven National Laboratory, Argonne National Laboratory, Charles University (Czech Republic), the Academy of Sciences of the Czech Republic, and Dublin City University (Ireland) also worked on the study.

The research was carried out in part at the Center for Nanophase Materials Sciences at Oak Ridge National Laboratory and the Advanced Photon Source at ANL—both U.S. Department of Energy facilities. Funding came from UT via the Transdisciplinary Academy Program and the Organized Research Unit Program, as well as from DOE and the U.S. Department of Defense.

Across disciplines, countries, universities, national labs, and levels of experience, researchers pooled their expertise and resources to further investigate a theory proposed 20 years ago. The results not only reveal more about the science of magnetism, but also offer the possibility of using those findings to improve everyday devices.

X
X
X
  • Filters

  • × Clear Filters

How a Molecular Signal Helps Plant Cells Decide When to Make Oil

Scientists identify new details of how a sugar-signaling molecule helps regulate oil production in plant cells. The work could point to new ways to engineer plants to produce substantial amounts of oil for use as biofuels or in the production of other oil-based products.

Neutrons Produce First Direct 3D Maps of Water During Cell Membrane Fusion

New 3D maps of water distribution during cellular membrane fusion could lead to new treatments for diseases associated with cell fusion. Using neutron diffraction at Oak Ridge National Laboratory, scientists made the first direct observations of water in lipid bilayers modeling cell membrane fusion.

Chemists Demonstrate Sustainable Approach to Carbon Dioxide Capture From Air

Chemists at Oak Ridge National Laboratory have demonstrated a practical, energy-efficient method of capturing carbon dioxide directly from air. If deployed at large scale and coupled to geologic storage, the technique may bolster the portfolio of responses to global climate change.

Nucleation a boon to sustainable nanomanufacturing

Young-Shin Jun, professor of energy, environmental & chemical engineering in the School of Engineering & Applied Science, and Quingun Li, a former doctoral student in her lab, are the first to measure the activation energy and kinetic factors of calcium carbonate's nucleation, both key to predicting and controlling the process.

Breaking the Symmetry Between Fundamental Forces

Scientists improve our understanding of the relationship between fundamental forces by re-creating the earliest moments of the universe.

Greater Than the Sum of Its Parts

Argonne scientists and their collaborators have developed a new model that merges basic electrochemical theory with theories used in different contexts, such as the study of photoelectrochemistry and semiconductor physics, to describe phenomena that occur in any electrode.

A prize-winning measurement device could aid a wide range of industries

Companies dealing with liquids ranging from wastewater to molten metals could benefit from a prize-winning device developed by researchers at the U.S. Department of Energy's (DOE) Princeton Plasma Physics Laboratory (PPPL) and Princeton University.

After 150 years, a Breakthrough in Understanding the Conversion of CO2 to Electrofuels

Using surface-enhanced Raman spectroscopy, Columbia Engineers are first to observe how CO2 is activated at the electrode-electrolyte interface; their finding shifts the catalyst design from trial-and-error paradigm to a rational approach and could lead to alternative, cheaper, and safer renewable energy storage.

Water Plays Unexpected Role in Forming Minerals

Water molecules line up tiny particles to attach and form minerals; understanding how this happens impacts energy extraction and storage along with waste disposal.

X-Rays Uncover a Hidden Property That Leads to Failure in a Lithium-Ion Battery Material

X-ray experiments at the Department of Energy's SLAC National Accelerator Laboratory and Lawrence Berkeley National Laboratory have revealed that the pathways lithium ions take through a common battery material are more complex than previously thought.


  • Filters

  • × Clear Filters

Berkeley Lab to Build an Advanced Quantum Computing Testbed

Lawrence Berkeley National Laboratory (Berkeley Lab) will receive $30 million over five years from the U.S. Department of Energy to build and operate an Advanced Quantum Testbed (AQT) allowing researchers to explore superconducting quantum processors to advance scientific research

Cheng wins Midwest Energy News' 40 Under 40 Award

Lei Cheng, an assistant chemist in the Materials Science division at the U.S. Department of Energy's (DOE) Argonne National Laboratory, has received a Midwest Energy News 40 Under 40 Award.

JCESR renewed for another five years

The U.S. Department of Energy (DOE) today announced its decision to renew the Joint Center for Energy Storage Research (JCESR), a DOE Energy Innovation Hub led by Argonne National Laboratory and focused on advancing battery science and technology.

Binghamton designated as NextFlex New York Node for flexible hybrid electronics initiative

NextFlex has designated Binghamton University to be the New York "Node" for its flexible hybrid electronics (FHE) initiative. As the NextFlex New York Node, Binghamton will design, develop and manufacture tools; process materials and products for flexible hybrid electronics; and attract, train and employ an advanced manufacturing workforce, building on the region's existing electronics manufacturing base.

First Particle Tracks Seen in Prototype for International Neutrino Experiment

The largest liquid-argon neutrino detector in the world has just recorded its first particle tracks, signaling the start of a new chapter in the story of the international Deep Underground Neutrino Experiment (DUNE). DUNE's scientific mission is dedicated to unlocking the mysteries of neutrinos, the most abundant (and most mysterious) matter particles in the universe.

Tais Gorkhover Wins LCLS Young Investigator Award for Pioneering Novel X-ray Imaging Methods

Tais Gorkhover, a principal investigator with the Stanford PULSE Institute, will receive the 2018 LCLS Young Investigator Award, granted to early-career scientists in recognition of exceptional research using the Linac Coherent Light Source (LCLS) X-ray free-electron laser at the Department of Energy's SLAC National Accelerator Laboratory.

ORNL, United Kingdom Lab Partner on Nuclear Energy Research

The United Kingdom's National Nuclear Laboratory and the U.S. Department of Energy's Oak Ridge National Laboratory have agreed to cooperate on a wide range of nuclear energy research and development efforts that leverage both organizations' unique expertise and capabilities.

Nat Fisch receives Fusion Power Associates' Distinguished Career Award

Feature describes lifetime career award for PPPL physicist and professor Nat Fisch.

Wells Fargo Innovation Incubator Expands Focus to Include the Food-Water-Energy Interconnection

The Wells Fargo Innovation Incubator (IN2), a technology incubator and platform funded by the Wells Fargo Foundation and administered by the National Renewable Energy Laboratory (NREL), is expanding its program to advance technologies that address the interconnection of food, water and energy.

Graham George receives Lytle Award for contributions to X-ray absorption spectroscopy

Graham Neil George, professor and Canada Research Chair in X-ray Absorption Spectroscopy (XAS) at the University of Saskatchewan, has been chosen to receive the 2018 Farrel W. Lytle Award for his outstanding contributions to synchrotron science at the Department of Energy's SLAC National Accelerator Laboratory.


  • Filters

  • × Clear Filters

Breaking the Symmetry Between Fundamental Forces

Scientists improve our understanding of the relationship between fundamental forces by re-creating the earliest moments of the universe.

Water Plays Unexpected Role in Forming Minerals

Water molecules line up tiny particles to attach and form minerals; understanding how this happens impacts energy extraction and storage along with waste disposal.

Heavy Particles Get Caught Up in the Flow

First direct measurement show how heavy particles containing a charm quark get caught up in the flow of early universe particle soup.

Seeing Between the Atoms

New detector enables electron microscope imaging at record-breaking resolution.

Scaling Up Single-Crystal Graphene

New method can make films of atomically thin carbon that are over a foot long.

Discovered: Optimal Magnetic Fields Suppress Instabilities in Tokamak Plasmas

U.S. and Korean scientists show how to find and use beneficial 3-D field perturbations to stabilize dangerous edge-localized modes in plasma.

New Electron Glasses Sharpen Our View of Atomic-Scale Features

A new approach to atom probe tomography promises more precise and accurate measurements vital to semiconductors used in computers, lasers, detectors, and more.

Getting an Up-Close, 3-D View of Gold Nanostars

Scientists can now measure 3-D structures of tiny particles with properties that hold promise for advanced sensors and diagnostics.

Small, Short-Lived Drops of Early Universe Matter

Particle flow patterns suggest even small-scale collisions create drops of early universe quark-gluon plasma.

Tuning Terahertz Beams with Nanoparticles

Scientists uncover a way to control terahertz radiation using tiny engineered particles in a magnetic field, potentially opening the doors for better medical and environmental sensors.


Spotlight

Friday September 21, 2018, 01:05 PM

"Model" students enjoy Argonne campus life

Argonne National Laboratory

Thursday September 06, 2018, 01:05 PM

Writing Code for a More Skilled and Diverse STEM Workforce

Brookhaven National Laboratory

Tuesday September 04, 2018, 11:30 AM

New graduate student summer school launches at Princeton Plasma Physics Laboratory

Princeton Plasma Physics Laboratory

Friday August 31, 2018, 06:05 PM

The Gridlock State

California State University (CSU) Chancellor's Office

Friday August 31, 2018, 02:05 PM

Meet Jasmine Hatcher and Trishelle Copeland-Johnson

Brookhaven National Laboratory

Friday August 24, 2018, 11:05 AM

Argonne hosts Modeling, Experimentation and Validation Summer School

Argonne National Laboratory

Wednesday August 22, 2018, 01:05 PM

Students affected by Hurricane Maria bring their research to SLAC

SLAC National Accelerator Laboratory

Wednesday August 22, 2018, 10:05 AM

Brookhaven Lab Pays Tribute to 2018 Summer Interns

Brookhaven National Laboratory

Monday August 20, 2018, 12:05 PM

Changing How Buildings Are Made

Washington University in St. Louis

Thursday August 16, 2018, 12:05 PM

CSUMB Selected to Host Architecture at Zero Competition in 2019

California State University, Monterey Bay

Friday July 20, 2018, 03:00 PM

Department of Energy Invests $64 Million in Advanced Nuclear Technology

Rensselaer Polytechnic Institute (RPI)

Thursday July 19, 2018, 05:00 PM

Professor Miao Yu Named the Priti and Mukesh Chatter '82 Career Development Professor

Rensselaer Polytechnic Institute (RPI)

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





Showing results

0-4 Of 2215