Scientists discover hidden magnetic waves in high-temperature superconductors

Aug 05, 2013
In this rendering, never-before-seen magnetic excitations ripple through a high-temperature superconductor, revealed for the first time by the Resonant Inelastic X-ray Scattering technique. By measuring the precise energy change of beams of incident x-rays (blue arrow) as they struck these quantum ripples and bounced off (red arrow), scientists discovered excitations present throughout the entire LSCO phase diagram.

Intrinsic inefficiencies plague current systems for the generation and delivery of electricity, with significant energy lost in transit. High-temperature superconductors (HTS)—uniquely capable of transmitting electricity with zero loss when chilled to subzero temperatures—could revolutionize the planet's aging and imperfect energy infrastructure, but the remarkable materials remain fundamentally puzzling to physicists. To unlock the true potential of HTS technology, scientists must navigate a quantum-scale labyrinth and pin down the phenomenon's source.

Now, scientists at the U.S. Department of Energy's (DOE) Brookhaven National Laboratory and other collaborating institutions have discovered a surprising twist in the magnetic properties of HTS, challenging some of the leading theories. In a new study, published online in the journal Nature Materials on August 4, 2013, scientists found that unexpected —quantum waves believed by many to regulate HTS—exist in both non-superconducting and .

"This is a major experimental clue about which magnetic excitations are important for high-temperature superconductivity," said Mark Dean, a physicist at Brookhaven Lab and lead author on the new paper. "Cutting-edge x-ray scattering techniques allowed us to see excitations in samples previously thought to be essentially non-magnetic."

On the , electron spins—a bit like tiny bar magnets pointed in specific directions—rapidly interact with each other throughout magnetic materials. When one spin rotates, this disturbance can propagate through the material as a wave, tipping and aligning the spins of neighboring electrons. Many researchers believe that this subtle excitation wave may bind electrons together to create the perfect current conveyance of HTS, which operates at slightly warmer temperatures than traditional superconductivity.

"Proving or disproving this hypothesis remains one of the holy grails of condensed matter physics research," Dean said. "This discovery gives us a new way to evaluate rival theories of HTS."

Perfectly dope

Superconductivity demands extremely cold conditions and a precise chemical recipe. Beyond selecting the right elements from the periodic table, physicists carefully tweak the electron content of atoms through a process called doping. Doping determines the average number of electrons present in each atom, and in turn dictates both the behavior of spin waves and the presence of HTS, which emerges around a particular doping sweet spot.

For this study, the team examined thin films of lanthanum, strontium, copper, and oxygen—often abbreviated as LSCO. These particular HTS materials can be tuned to exhibit a wide range of different electronic behaviors.

"This is the only system that lets us examine the entire phase diagram, from a strongly correlated insulator all the way to a non-superconducting metal," said Brookhaven physicist John Hill, coauthor on the paper. "We could measure magnetic excitations both before and after the ideal doping levels for superconductivity."

To grow these materials, Brookhaven Lab physicist Ivan Bozovic—another author on the study—used a custom-built atomic layer-by-layer molecular beam epitaxy machine (ALL-MBE). Bozovic's system is uniquely equipped to monitor the synthesis of the LSCO films in real-time, giving him an unparalleled degree of control over the atomic composition of each layer, including adjustments to the doping levels.

"Ivan grows these beautiful, fantastic films," Hill said. "His samples are highly uniform with flat, mirror-like surfaces. This helps enormously when trying to pin down the subtleties of how these samples scatter x-rays."

Measuring a quantum sea

The quantum ripples themselves have wavelengths measured on the Ångstrom scale—smaller than one billionth of a meter. To detect these tiny fluctuations, the scientists applied a technique called resonant inelastic x-ray scattering (RIXS) to the full range of LSCO films. The measurements were taken with the Advanced X-ray Emission Spectrometer at the European Synchrotron Radiation Facility (ESRF) in France. The design, construction, and commissioning of this instrument was led by Giacomo Ghiringhelli and Lucio Braicovich at the Politecnico di Milano in Italy and by Nick Brookes at the ESRF. The Brookhaven Lab team worked in close collaboration with these scientists to perform the RIXS measurements.

"This instrument allowed us to precisely measure how much energy the x-rays lost when they struck each LSCO sample," Dean said. "We could then pinpoint the presence or absence of magnetic excitations and track them across all the different doping levels."

Earlier studies using neutron scattering found that magnetic excitations appeared to vanish in the overdoped LSCO samples, bolstering the prominent theory that the waves play an essential role in superconductivity. The RIXS technique, however, is much more sensitive to magnetic excitations with certain wavelengths and capable of detecting otherwise imperceptible signals.

"Discovering excitations that do not depend on doping levels means that the relationship between HTS and the waves in these films is more intricate than we suspected," Hill said.

Brighter beams and better superconductors

RIXS is currently able to detect magnetic excitations with a precision, or energy resolution, of about 100 milli-electron volts. But as scientists seek more fundamental phenomena, even greater accuracy and sensitivity is required. Brookhaven Lab's National Synchrotron Light Source II (NSLS-II), expected to start operating in 2014, will produce some of the brightest x-rays in the world. The Soft Inelastic X-ray beamline under construction at NSLS-II promises unprecedented energy resolution for HTS investigations.

"Ultimately, the RIXS energy resolution is still not as good as we'd like," Dean said. "NSLS-II is going to be huge for the superconductivity game—absolutely huge. We'll be able to see excitations down at 10 milli-electron volts, and there should be real breakthroughs hidden there."

Solving the mystery of high-temperature superconductivity could radically improve technology ranging from wind turbines to medical imaging devices. But to manipulate the perfect electricity conveyance possible in HTS materials and possibly bring them up to room temperature, theorists must transform these experimental results into universally applicable rules.

"The joke is that HTS has in fact already been solved, but we just don't know which of the many competing theories is the right one," Hill said. "Our discovery was actually predicted by a few groups, and we're excited to see them leap on the results and drive our understanding forward. The work is fundamentally interesting, yes, but the potential applications are really exciting."

Explore further: Physicist pursues superconductivity mysteries

More information: Nature Materials (2013) doi:10.1038/nmat3723

Related Stories

Recommended for you

Scientists film magnetic memory in super slow-motion

2 hours ago

Researchers at DESY have used high-speed photography to film one of the candidates for the magnetic data storage devices of the future in action. The film was taken using an X-ray microscope and shows magnetic ...

User comments : 9

Adjust slider to filter visible comments by rank

Display comments: newest first

antialias_physorg
5 / 5 (3) Aug 05, 2013
scientists must navigate a quantum-scale labyrinth

I get what they mean, but that seems like a very small labyrinth. Aren't small labyrinths easier than large ones?
(it's much like when someone says they've made a 'quantum leap' in some field or other. While it's clear what they mean, if you were to take the expression at face value it would mean 'the smallest possible step forward')

but we just don't know which of the many competing theories is the right one," Hill said. "Our discovery was actually predicted by a few groups, and we're excited to see them leap on the results and drive our understanding forward.

That is as it should be. I fully agree. HTS has an enormous potential for transforming the future.
frostedpanda
1 / 5 (6) Aug 05, 2013
Room temperature superconductors should be viable if in considering the conditions forming the material in the physicality of it.By that I mean what is actually happening to bring about the condition. Cooling conditions draw the nucleus inward and tighten the crystalline structure.
Electron soup is all around everything, as they attenuate or diminuate, the conditions to become a "proton" occur, which draw in more electrons, which then speed up and attempt to squeeze into the proton's space.
Rather than get into that lets consider gadolinium and "giant magneto-caloric" materials
If we cold fusion barium (under pressurization) with impurities of magneto-caloric effect and fuse under conditions where this magnetic field is release at the moment of "decalesance" and induce a magnetic moment, should draw the core in tight. A high oxide content covering(yt,co) the core and a graphene coat should be that material. Anyone with the equipment?
Mark_Goldes
2 / 5 (4) Aug 05, 2013
Polymer Ultraconductors are patented equivalents of ambient temperature superconductors. They operate identically from close to Absolute Zero to 200 degrees C. They have made mainly as thin films to date. The conductivity is through the films in the thin direction. Tape and wire are on the horizon but await funding to resume the development program

Four SBIR Contracts have been successfully concluded, including a Phase II with the USAF.

Fractal systems independently produced almost 1,000 sample for the Air Force.

A theory consistent with 20 years of development was published by L.N. Grigorov, who discovered these materials, in Physical Research B, the oldest scientific publication in North America.

It will be interesting to see if someone at Brookhaven, or elsewhere, finds these magnetic waves in these remarkable polymers.

CHAVA Energy plans to resume development when sufficient capital becomes available.

Ultraconducting Magnetic Energy Storage might compete with batteries.

DarkHorse66
5 / 5 (2) Aug 06, 2013
..(it's much like when someone says they've made a 'quantum leap' in some field or other. While it's clear what they mean, if you were to take the expression at face value it would mean 'the smallest possible step forward')..

Actually, the word 'quantum' stems from the latin 'quantus', meaning 'how much'. I've also found a number of dictionary sites that allow for it include the definition of 'large', rather than just 'small ':
http://dictionary.../quantum
http://www.merria.../quantum
https://www.vocab.../quantum
'How much' could be used to quantify any amount or a size.eg 'how much mud is in that puddle?Ans: alot(amount) vs a big tubful(size)'.Those defs show that the word gets used to describe quantity as well as size words & those two terms are definitely interchangeable in the right context.It is only in physics that we use this more narrow definition. So beware, it's not just about tiny objects! :)
Cheers, DH66
no fate
3 / 5 (4) Aug 07, 2013
http://www.superc...rec.htm. From now the superconductors are getting hot.


They must have all rated you "1" because they don't speak english....or understand science. Nice link.

You will be hardpressed to find any place in the universe that doesn't have at least a miniscule amount of magnetic flux present.
Keyto Clearskies
1 / 5 (4) Aug 21, 2013
"For over 20 years Mark Goldes has claimed his company MPI has been developing machines that generate energy for free. In over 20 years his company has not presented one shred of evidence that they can build such machines...

"For the past five years Mark Goldes has been promising generators 'next year.' He has never delivered. Like 'Alice in Wonderland' there will always be jam tomorrow, but never jam today.

- Penny Gruber, December 2008

- Penny Gruber's comment was written almost five years ago - but it's just as true today - except that MPI, Goldes' corporation that he claimed would bring in one billion dollars in revenue from his imaginary generator in 2012, is now defunct, having never produced any "Magnetic Power Modules" - just as his company called "Room Temperature Superconductors Inc" is also now defunct, having never produced any "room temperature superconductors." Now Goldes has a new scamporation, Chava Energy.
antialias_physorg
5 / 5 (2) Aug 21, 2013
The physorg voting system is abused with voting trolls engaged in automated downvoting per account basis.

No. You tried that out yourself just a few weeks ago, remember? You changed accounts (yet again) and despite no one knowing it was you your posts were immediately downvoted.

Not because it's you, but because the content of your posts is howling insane.

It's not you. It's what you post. Get to grips with that.
Q-Star
not rated yet Aug 21, 2013
What do you think?


I thought ya were the very epitome of the intuitive side of science? Ya say so to us dozens of times every day. And ya can't intuit what he's thinking of your harebrained ravings and demented posturing? Ya can't be much of a science guy if ya your observational & critical thinking skills can take it in.
antialias_physorg
5 / 5 (1) Aug 22, 2013
Yep, my ideas are insane - the only question is whether they're insane enough to be true. What do you think?

To an insane person insane ideas will seem true.
To the rest of us...not so much.

So you can decide: are you the only sane person in an insane world (always taking into account that fact that this 'insane world' is getting stuff done and making scientific progress while you aren't...and that if you choose this path you may have to opt for megalomania instead of insanity - and probably require therapy)?

...or...

are your just insane (and probably require therapy)?

It's your choice. But therapy is in your future no matter what.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.