Spring 2004 – vol. 22, no. 1 logos home page Contact the logos editor Argonne home page Feature articles Superconductivity team wins top research prizes Creating stability in a world of unstable electricity distribution Argonne tests, creates fuel cells to power the future Fueling the hydrogen future with Argonne's ceramic membrane Nuclear plants may be clean hydrogen source Argonne Update Stars surrender secrets to supercomputers Electricity controls nanocrystal architecture

Superconductivity team wins top research prizes

by Rhianna Wisniewski

NOBELIST – Alexei Abrikosov accepts the 2003 Nobel Prize in physics from Swedish King Carl XVI Gustav.

Awards presented in 2003 to three Argonne scientists highlighted the excellence of Argonne's superconductivity program.

Distinguished Scientist Alexei Abrikosov shared the Nobel Prize in physics.

Materials Science Division Director George Crabtree was awarded the Kamerlingh Onnes Prize at the Seventh International Conference on Materials and Mechanisms of Superconductivity and High-Temperature Superconductors in Rio de Janiero, Brazil.

Senior scientist and Director of the Materials Theory Institute Valerii Vinokur accepted the John Bardeen Prize at the same conference in Brazil, and won a Humboldt Research Prize.

Superconductivity is the transfer of electric current without any loss. Standard copper conductors transfer electricity and create controlled magnetic fields, but they resist current flow, generating heat and wasting energy. Superconductors accomplish the same tasks without resistance or loss.

Abrikosov was awarded the Nobel Prize in physics for developing the theory to explain how magnetic fields penetrate certain superconducting materials. He shared the award with Anthony J. Leggett of the University of Illinois at Urbana-Champaign and Vitaly L. Ginzburg of the Lebedev Institute in Moscow. The three researchers were recognized for their work explaining matter's bizarre behavior at extremely low temperatures.

The distinguished scientist at the Condensed Matter Theory Group in Argonne's Materials Science Division, Abrikosov's research centers on the structure and behavior of solids and liquids, called condensed-matter physics, and he concentrates on superconductivity. He was the first to propose the concept of "type-II superconductors" in 1952 and constructed the theory of their magnetic properties, known as Abrikosov vortex lattices.

When first proposed, his theory was considered controversial, and Abrikosov said "I put it in a drawer, but I did not put it in a wastebasket, because I believed in it."

"Alex's insights and discoveries have launched 50 years of studies into the fundamental nature of superconductivity," said Thomas F. Rosenbaum, the University of Chicago's vice president for research and for Argonne National Laboratory.

Alexei Abrikosov in his office.

The Onnes and Bardeen prizes are awarded once every three years by independent committees. They recognize experimental and theoretical work, respectively, that has provided the most significant insight into the nature of superconductivity. Crabtree's Onnes award acknowledged his pioneering experiments on patterns formed by Abrikosov vortices as they penetrate superconductors. Valerii Vinokur received the John Bardeen Prize for his influential contributions to vortex matter theory.

"To have Argonne recognized in both theory and experiment by the superconductivity community in the same year is truly monumental," Crabtree said.

Argonne's double honor is the result of pioneering experimental and theoretical work that focuses on vortex matter, Crabtree explained. Vortices are whirlpools of electrons circulating around tubes of magnetic flux that form in many superconductors when they are placed in a magnetic field. Each vortex contains one unit, or quantum, of magnetic flux. All electromagnetic properties of superconductors are based on the behavior of these vortices.

Crabtree's award-winning research stemmed from experiments that he and his colleagues performed to see vortex-lattice melting in various temperatures, magnetic fields and degrees of disorder.

Vortex lines in superconductors form a regular array of hexagonal patterns known as lattices. Upon heating the vortex lattices in certain copper oxide superconductors to between 60 and 90 degrees Kelvin (minus 353 and minus 298 degrees Fahrenheit), Crabtree and his colleagues found that the lattices melt, just as ice melts to water.

The vortex liquid above the melting point is a new phase of vortex matter. Its properties are very different from those of the vortex lattice - it flows freely in response to even the smallest driving force. This motion of the vortex liquid produces resistance, a feature exploited in the Argonne experiments to detect its presence. Like other liquids, the vortex liquid moves easily around obstacles and finds meandering paths of least resistance in complicated landscapes.

Vortex lattice melting and the behavior of the liquid phase are strikingly different from anything previously encountered in superconductivity. In high-temperature superconductors, the vortex liquid is the dominant feature of the superconducting state. It provides fertile ground for innovative concepts, experiments and applications.