Superconductivity team wins top research prizes
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Vinokur's Bardeen award was the result of a discovery he made with his colleagues; they found that disorder dramatically alters vortex matter resistance. Their theories predicted an effect of disorder on the lattice structure similar to the effect of a bumpy road on a car, a phenomenon they called "dynamic melting."
 VORTICES – Magnetic fields penetrate superconductors in concentrated tubes called vortices. Each vortex consists of a tube of magnetic field surrounded by a circulating superconducting current that flows with zero resistance. |
"If you drive fast enough," Vinokur explained, "it's easy on the car. If you drive very slowly, pay attention to every bump, it's also easy on the car. But you'll discover some intermediate speed that is very unpleasant for you and the car."
Vinokur said the same effect occurs with a vortex lattice. Pushed hard enough it can overcome any disorder in the superconductor. Pushed very slowly, it will adjust to disorder. But if it is driven at some in-between speed, disorder takes the lattice apart and it "melts."
In "first gear," the vortex lattice slowly creeps across bumps due to disorder. Vinokur and his colleagues discovered that the energy barriers controlling this slow motion exhibit a universal "scaling" behavior as a function of the driving force, which is a general feature common to all disordered systems. This finding was crucial to understanding phenomena at the melting point, a feature early emphasized by Vinokur.
These prizes have never before been awarded to two scientists at the same institution in the same year. Vinokur said that he feels this award marks the recognition of ground-breaking ideas that no one previously accepted.
"I was thrilled when I looked at the previous recipients of the prize," Vinokur said. "They were scientists whose contributions to the field of theoretical physics in the last 50 years were determining and crucial for its further development. I was honored to be recognized as on a par with people like that."
Abrikosov won the John Bardeen Award in 1991, the first year it was awarded.
Later in 2003, Vinokur was recognized by the Alexander von Humboldt Foundation for his work in superconductivity and nanophysics. Nanomaterials - measured in billionths-of-a-meter - behave differently when compared to their more traditional counterparts. The value, quality and international impact of the nanophysics program Vinokur established at Argonne played an important role in Vinokur's recognition.
 AWARD WINNERS – George Crabtree (left) and Valerii Vinokur are other members of Argonne's winning high-temperature superconductivity team. |
Vinokur plans to use his award money to spark collaboration between German scientists and the Materials Theory Institute he heads.
These distinctions come on top of the many honors Argonne has received for its superconductivity program through the years. Currently, Argonne's superconductivity scientists are among the world's most often cited and are invited to give talks all over the world.
Both Vinokur and Crabtree emphasize that Argonne's programs in vortex matter are collaborative efforts. "Success requires a critical mass of excellent scientists all working together," Crabtree said. "We are fortunate to have such a group at Argonne."
"Exchange of ideas is highly encouraged at Argonne," Abrikosov said. "It is useful to have both theorists and experimenters working together. Argonne is unusual in that the environment is conducive to joint work."
Abrikosov explained that when he began working at the laboratory, he had not imagined the number of experiments being performed. He said that he felt proud that he was able to help the scientists here make sense of their experiments and discoveries.
Collaboration is key
Both Crabtree and Vinokur attribute the laboratory's exceptional superconductivity program to close interactions between theorists and experimentalists.
"Collaboration is simply integral to this program," Crabtree said. "If experimentalists and theorists did not meet daily in the hallways and over coffee, we would not have the same level of teamwork."
The dramatic development of vortex physics at Argonne over the last 10 years echoes similar breakthrough progress at the laboratory across the field of superconductivity. The discovery of high-temperature superconductors in 1986 shook the foundations of the field. Within months, the highest temperature at which a material became superconducting jumped from 23 K (minus 418 F) to 93 K (minus 292 F) and later rose to 160 K (minus 172 F). Traditional concepts that had guided the field for 30 years were suddenly outmoded.
"It was a magic time, a once-in-a-lifetime opportunity," said Crabtree. "We saw the enormous promise of the field and the chance to make a lasting contribution."
Argonne leaped ahead, not only in vortex matter but also in synthesizing new materials, developing innovative experiments and advancing creative theory.
The laboratory's materials synthesis program devised new methods for controlling the subtle variations in composition and structure that govern superconducting properties. These forefront materials enabled state-of-the-art experiments at Argonne and around the world. Laboratory scientists explored exotic features of the high-temperature superconducting state, such as its vanishing density of superconducting electrons along certain crystallographic directions, and its ability to carry large electrical currents at zero resistance even in high magnetic fields.
"It is the integration of materials, experiments and theory under one roof that gives Argonne its scientific and technological power," said Crabtree. "This is a defining feature of national laboratories that few other research institutions share."
For more information, please contact Catherine Foster (630/252-5580 or media@anl.gov) at Argonne.
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