Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A supra new kind of froth

09.06.2008
US Department of Energy's Ames Laboratory physicists propose model froth system

To see the latest science of type-I superconductors, look no further than the froth on a morning cup of cappuccino. A team of U.S. Department of Energy's Ames Laboratory physicists and collaborating students have found that the bubble-like arrangement of magnetic domains in superconducting lead exhibits patterns that are very similar to everyday froths like soap foam or frothed milk on a fancy coffee.

The similarities between the polygonal-shaped patterns in conventional foams and "suprafroths," the patterns created by a magnetic field in a superconductor, establish suprafroths as a model system for the study of froths.

"There are certain statistical laws that govern the behavior of froths, and we found that suprafroths satisfy these laws," said Ruslan Prozorov, Ames Laboratory physicist and primary investigator. "We can now apply what we know of suprafroths to all other froths and complex froth-like systems."

Prozorov discovered the suprafroth pattern last year, seeing an unexpected foam-like design when he applied a magnetic field to a lead sample in a magneto-optics system. Since the term "superfroth" was already in use for an unrelated product, Prozorov coined "suprafroths" in a nod to history: in the 1930s, superconductors were called "supraconductors."

To help characterize suprafroths, Prozorov pulled together a team including Ames Lab senior physicist Paul Canfield, summer laboratory assistant Andrew Fidler and graduate student Jacob Hoberg.

Canfield, who has an interest in pattern formation in nature, supplied the original idea to compare suprafroths' patterns to conventional froths.

"Last year, we were standing by Ruslan's poster on equilibrium patterns in Pb (lead), and I was discussing one of his figures during a break," said Canfield. "I recognized that the patterns he was showing for his Pb sample were exceptionally similar to that of a classical picture of bubbles.

"At first Ruslan was skeptical, but over the next few weeks we both realized just how profound the similarity between suprafroths and conventional froths was." Canfield continued.

The team's analysis revealed that suprafroths behave similarly to other commonplace froths, despite their very different microscopic origins: traditional froths' cell walls consist of material like detergent, water or plastic, while suprafroths' cell boundaries consist of superconducting phase lead.

One similarity between suprafroths and conventional froths is the process of coarsening, or when froth cells grow or shrink and eventually disappear. In everyday froths, this process is evident in a sink full of dish soap bubbles that pop and disappear over time. The process is similar in suprafroths when magnetic field is increased, illustrating that suprafroths adhere to John von Neumann's law, the widely accepted concept in froth physics that specifies the rate at which froth cells grow or shrink.

"Seeing von Neumann's law at work in suprafroths shows that the froth state is really an intrinsic property of this superconductor," said Prozorov.

"Suprafroths, like regular foams, adhere to the concept of area tiling that says that if you want to cover a plane with polygons with each having three vertices, the most probable polygon is a hexagon," he continued.

Physicists have long believed in a connection between the two statistical rules of froths. Common understanding has been that the most probable polygon—the hexagon—was related to the number of sides—six—that determines whether a froth cell shrinks or grows during coarsening. But the Ames Lab team's analysis has decoupled these two concepts in suprafroths.

"In our suprafroths, we found that the association between these two ideas is a coincidence, said Prozorov. "There is no strict correspondence between the most stable type of froth cell and the most common number of sides in a froth cell."

In suprafroths, cells of all observed numbers of sides grow with an increase in magnetic field, a discovery marking an important contribution to the general study of froths.

But the most significant contribution suprafroths make to the general physics of froth is as a model system that can be used to study all froths. Suprafroths offer reversibility, a significant benefit over conventional froths.

"In everyday froths, like soap foam, the agent of change is time," said Prozorov. "You have to wait for bubbles to simply dry out, and that takes days. And it's not reversible. You cannot reverse time."

"Once the bubbles pop, the problem is that the physical and chemical properties of the cells get modified, so that doesn't make for a clean experiment," Prozorov continued. "In an ideal situation, you want to only study the properties of the froth patterns and their complexity. You want to easily be able to change some parameter and change the structure of the froth."

Achieving an ideal froth experiment is possible in suprafroths because the agents that create the superconducting phase cells are magnetic field and temperature, both reversible parameters.

"Magnetic field and temperature can be tuned in the lab," said Prozorov. "They can be increased or decreased, and therefore we are able to study the pure statistical properties of froth without problems associated with the irreversibility of time or with chemical property changes."

Prozorov's comparison of suprafroths is also an important contribution is the study of superconductors.

"The statistical analysis shows suprafroths behave just like normal froth, which is also new for superconductivity," said Prozorov. "Just last year we found this new pattern in superconductors, and now we've proven that the froth state is really an intrinsic property of superconducting lead. It's a big deal for both the general physics of froth and the growing physics of superconductors.

"In physics, if you can find model systems, like suprafroths, that have similar patterns, then by studying these model systems you can actually get additional information about the behavior of very complex systems like galaxies, geophysics or biophysics" said Prozorov. "So, the bottom line is that studying physics of everyday soap froth, or, more reliably, suprafroths, can help us understand very complex, difficult questions about the world around us."

Canfield said that the suprafroth project is a case study for how collaboration should work at research laboratories.

"Fruitful collaboration like this happens frequently at Ames Lab," he said. "As part of our extensive collaboration and interaction, Ruslan and I discuss ideas, materials and results all the time."

Kerry Gibson | EurekAlert!
Further information:
http://www.nature.com/nphys/journal/v4/n4/full/nphys888.html
http://www.cmpgroup.ameslab.gov/supermaglab/video/Pb.html

More articles from Physics and Astronomy:

nachricht New Insight into Molecular Processes
21.11.2018 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht Exoplanet stepping stones
21.11.2018 | W. M. Keck Observatory

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First diode for magnetic fields

Innsbruck quantum physicists have constructed a diode for magnetic fields and then tested it in the laboratory. The device, developed by the research groups led by the theorist Oriol Romero-Isart and the experimental physicist Gerhard Kirchmair, could open up a number of new applications.

Electric diodes are essential electronic components that conduct electricity in one direction but prevent conduction in the opposite one. They are found at the...

Im Focus: Nonstop Tranport of Cargo in Nanomachines

Max Planck researchers revel the nano-structure of molecular trains and the reason for smooth transport in cellular antennas.

Moving around, sensing the extracellular environment, and signaling to other cells are important for a cell to function properly. Responsible for those tasks...

Im Focus: UNH scientists help provide first-ever views of elusive energy explosion

Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.

Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...

Im Focus: A Chip with Blood Vessels

Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.

Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...

Im Focus: A Leap Into Quantum Technology

Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.

In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Optical Coherence Tomography: German-Japanese Research Alliance hosted Medical Imaging Conference

19.11.2018 | Event News

“3rd Conference on Laser Polishing – LaP 2018” Attracts International Experts and Users

09.11.2018 | Event News

On the brain’s ability to find the right direction

06.11.2018 | Event News

 
Latest News

Helping to Transport Proteins Inside the Cell

21.11.2018 | Life Sciences

Meta-surface corrects for chromatic aberrations across all kinds of lenses

21.11.2018 | Power and Electrical Engineering

Removing toxic mercury from contaminated water

21.11.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>