Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Strange electrons break the crystal symmetry of high-temperature superconductors: Brookhaven Lab scientists discover spontaneous voltage perpendicular to applied current that may help unravel the mystery of high-temperature superconductors

Brookhaven Lab scientists (from left) Ivan Bozovic, Xi He, Jie Wu, and Anthony Bollinger with the atomic layer-by-layer molecular beam epitaxy system used to synthesize the superconducting cuprate samples.
CREDIT
Brookhaven National Laboratory
Brookhaven Lab scientists (from left) Ivan Bozovic, Xi He, Jie Wu, and Anthony Bollinger with the atomic layer-by-layer molecular beam epitaxy system used to synthesize the superconducting cuprate samples. CREDIT Brookhaven National Laboratory

Abstract:
The perfect performance of superconductors could revolutionize everything from grid-scale power infrastructure to consumer electronics, if only they could be coerced into operating above frigid temperatures. Even so-called high-temperature superconductors (HTS) must be chilled to hundreds of degrees Fahrenheit below zero.

Strange electrons break the crystal symmetry of high-temperature superconductors: Brookhaven Lab scientists discover spontaneous voltage perpendicular to applied current that may help unravel the mystery of high-temperature superconductors

Upton, NY | Posted on July 27th, 2017

Now, scientists from the U.S. Department of Energy's (DOE) Brookhaven National Laboratory and Yale University have discovered new, surprising behavior by electrons in a HTS material. The results, published July 27 in the journal Nature, describe the symmetry-breaking flow of electrons through copper-oxide (cuprate) superconductors. The behavior may be linked to the ever-elusive mechanism behind HTS.

"Our discovery challenges a cornerstone of condensed matter physics," said lead author and Brookhaven Lab physicist Jie Wu. "These electrons seem to spontaneously 'choose' their own paths through the material -- a phenomenon in direct opposition to expectations."

Off-road electrons

In simple metals, electrons move evenly and without directional preference -- think of a liquid spreading out on a surface. The HTS materials in this study are layered with four-fold rotational symmetry of the crystal structure. Electric current is expected to flow uniformly parallel to these layers -- but this is not what the Brookhaven group observed.

"I'm from the Midwest, where miles of farmland separate the cities," said Brookhaven physicist and study coauthor Anthony Bollinger. "The country roads between the cities are largely laid out like a grid going north-to-south and east-to-west. You expect cars to follow the grid, which is tailor-made for them. This symmetry breaking is as if everyone decided to leave the paved roads and drive straight across farmers' fields."

In another twist, the symmetry-breaking voltage persisted up to room temperature and across the whole range of chemical compositions the scientists examined.

"The electrons somehow coordinate their movement through the material, even after the superconductivity fails," said Wu.

Strong electron-electron interactions may help explain the preferential direction of current flow. In turn, these intrinsic electronic quirks may share a relationship with HTS phenomena and offer a hint to decoding its unknown mechanism.

Seeking atomic perfection

Unlike well-understood classical superconductivity, HTS has puzzled scientists for more than three decades. Now, advanced techniques are offering unprecedented insights.

"The most difficult part of the whole work -- and what helps set us apart -- was the meticulous material synthesis," said study coauthor Xi He.

This work was a part of a larger project that took 12 years and encompassed the synthesis and study of more than 2,000 films of lanthanum-strontium-copper-oxide superconductors.

"This scale of research is well-suited to a national laboratory environment," said Ivan Bozovic, who leads the Brookhaven group behind the effort.

They use a technique called molecular beam epitaxy (MBE) to assemble complex oxides one atomic layer at a time. To ensure structural perfection, the scientists characterize the materials in real time with electron diffraction, where an electron beam strikes the sample and sensitive detectors measure precisely how it scatters.

"The material itself is our foundation, and it must be as flawless as possible to guarantee that the observed properties are intrinsic," Bozovic said. "Moreover, by virtue of our 'digital' synthesis, we engineer the films at the atomic-layer level, and optimize them for different studies."

Swimming against the current

The first major result of this comprehensive study by the MBE group at Brookhaven was published in Nature last year. It demonstrated that the superconducting state in copper-oxide materials is quite unusual, challenging the standard understanding.

That finding suggested that the so-called "normal" metallic state, which forms above the critical temperature threshold at which superconductivity breaks down, might also be extraordinary. Looking carefully, the scientists observed that as external current flowed through the samples, a spontaneous voltage unexpectedly emerged perpendicular to that current.

"We first observed this bizarre voltage over a decade ago, but we and others discounted that as some kind of error," Bollinger said. "But then it showed up again, and again, and again -- under increasingly controlled conditions -- and we ran out of ways to explain it away. When we finally dove in, the results exceeded our expectations."

To pin down the origin of the phenomenon, the scientists fabricated and measured thousands of devices patterned out of the HTS films. They studied how this spontaneous voltage depends on the current direction, temperature, and the chemical composition (the level of doping by strontium, which controls the electron density). They also varied the type and the crystal structure of the substrates on which the HTS films are grown, and even how the substrates are polished.

These meticulous studies showed beyond doubt that the effect is intrinsic to the HTS material itself, and that its origin is purely electronic.

At the molecular level, common liquids look the same in every direction. Some, however, are comprised of rod-like molecules, which tend to align in one preferred direction. Such materials are called liquid crystals -- they polarize light and are widely used in displays. While electrons in common metals behave as a liquid, in cuprates they behave as an electronic liquid crystal.

"We need to understand how this electron behavior fits into the HTS puzzle as a whole," He said. "This study gives us new ideas to pursue and ways to tackle what may be the biggest mystery in condensed matter physics. I'm excited to see where this research takes us."

###

Authors Bozovic and He share affiliation with Brookhaven Lab and Yale University.

The research was funded by DOE's Office of Science.

####

About Brookhaven National Laboratory
Brookhaven National Laboratory is supported by the Office of Science of the U.S. Department of Energy. The 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 science.energy.gov.

For more information, please click here

Contacts:
Ariana Tantillo

631-344-2347

Copyright © Brookhaven National Laboratory

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

Photonic chip guides single photons, even when there are bends in the road February 16th, 2018

Arrowhead Receives Regulatory Clearance to Begin Phase 1/2 Study of ARO-HBV for Treatment of Hepatitis B February 15th, 2018

Arrowhead Pharmaceuticals Receives Orphan Drug Designation for ARO-AAT February 15th, 2018

European & Korean Project To Demo World’s First 5G Platform During Winter Games February 15th, 2018

Laboratories

Atomic Flaws Create Surprising, High-Efficiency UV LED Materials: Subtle surface defects increase UV light emission in greener, more cost-effective LED and catalyst materials February 8th, 2018

Thanks for the memory: NIST takes a deep look at memristors January 20th, 2018

Laboratory Management Web Application Goes Nationwide January 9th, 2018

NRL improves optical efficiency in nanophotonic devices January 4th, 2018

Superconductivity

Ames Laboratory, UConn discover superconductor with bounce October 25th, 2017

Nagoya physicists resolve long-standing mystery of structure-less transition: Nagoya University-led team of physicists use a synchrotron radiation X-ray source to probe a so-called 'structure-less' transition and develop a new understanding of molecular conductors August 21st, 2017

Iron secrets behind superconductors unlocked July 7th, 2017

Brookhaven Scientists Study Role of 'Electrolyte Gating' in Functional Oxide Materials July 3rd, 2017

Govt.-Legislation/Regulation/Funding/Policy

Arrowhead Receives Regulatory Clearance to Begin Phase 1/2 Study of ARO-HBV for Treatment of Hepatitis B February 15th, 2018

Arrowhead Pharmaceuticals Receives Orphan Drug Designation for ARO-AAT February 15th, 2018

Rutgers-Led Innovation Could Spur Faster, Cheaper, Nano-Based Manufacturing: Scalable and cost-effective manufacturing of thin film devices February 14th, 2018

Understanding brain functions using upconversion nanoparticles: Researchers can now send light deep into the brain to study neural activities February 14th, 2018

Possible Futures

Photonic chip guides single photons, even when there are bends in the road February 16th, 2018

'Living bandages': NUST MISIS scientists develop biocompatible anti-burn nanofibers February 15th, 2018

Rutgers-Led Innovation Could Spur Faster, Cheaper, Nano-Based Manufacturing: Scalable and cost-effective manufacturing of thin film devices February 14th, 2018

Understanding brain functions using upconversion nanoparticles: Researchers can now send light deep into the brain to study neural activities February 14th, 2018

Chip Technology

Photonic chip guides single photons, even when there are bends in the road February 16th, 2018

Graphene on toast, anyone? Rice University scientists create patterned graphene onto food, paper, cloth, cardboard February 13th, 2018

Liquid crystal molecules form nano rings: Quantized self-assembly enables design of materials with novel properties February 7th, 2018

Nanometrics Selected for Fab-Wide Process Control Metrology by Domestic China 3D-NAND Manufacturer: Latest Fab Win Includes Comprehensive Suite for Substrate, Thin Film and Critical Dimension Metrology February 7th, 2018

Discoveries

Photonic chip guides single photons, even when there are bends in the road February 16th, 2018

'Living bandages': NUST MISIS scientists develop biocompatible anti-burn nanofibers February 15th, 2018

Rutgers-Led Innovation Could Spur Faster, Cheaper, Nano-Based Manufacturing: Scalable and cost-effective manufacturing of thin film devices February 14th, 2018

Understanding brain functions using upconversion nanoparticles: Researchers can now send light deep into the brain to study neural activities February 14th, 2018

Announcements

Photonic chip guides single photons, even when there are bends in the road February 16th, 2018

Arrowhead Receives Regulatory Clearance to Begin Phase 1/2 Study of ARO-HBV for Treatment of Hepatitis B February 15th, 2018

Arrowhead Pharmaceuticals Receives Orphan Drug Designation for ARO-AAT February 15th, 2018

European & Korean Project To Demo World’s First 5G Platform During Winter Games February 15th, 2018

Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers

Photonic chip guides single photons, even when there are bends in the road February 16th, 2018

'Living bandages': NUST MISIS scientists develop biocompatible anti-burn nanofibers February 15th, 2018

Rutgers-Led Innovation Could Spur Faster, Cheaper, Nano-Based Manufacturing: Scalable and cost-effective manufacturing of thin film devices February 14th, 2018

Understanding brain functions using upconversion nanoparticles: Researchers can now send light deep into the brain to study neural activities February 14th, 2018

Energy

Round-the-clock power from smart bowties February 5th, 2018

Silk fibers could be high-tech ‘natural metamaterials’ January 31st, 2018

A simple new approach to plastic solar cells: Osaka University researchers intelligently design new highly efficient organic solar cells based on amorphous electronic materials with potential for easy printing January 28th, 2018

Nature paper by Schlumberger researchers used photothermal based nanoscale IR spectroscopy to analyze heterogeneous process of petroleum generation January 23rd, 2018

Research partnerships

Rutgers-Led Innovation Could Spur Faster, Cheaper, Nano-Based Manufacturing: Scalable and cost-effective manufacturing of thin film devices February 14th, 2018

Understanding brain functions using upconversion nanoparticles: Researchers can now send light deep into the brain to study neural activities February 14th, 2018

Vanadium dioxyde: A revolutionary material for tomorrow's electronics: Phase-chance switch can now be performed at higher temperatures February 5th, 2018

Nanowire LED Innovator Aledia Announces €30 ($36M) Million Series-C Financing: Intel Capital Joins Existing Investors to Commercialize Certain Nanowire-LED Technologies for Mobile Displays January 29th, 2018

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