Chemistry – Page 127 – Science Spot

While this year’s Chemistry Prize is essentially biological, there are elements of chemistry in the award of the Physics Prize to Alexei A. Abrikosov (75) of the Argonne National Laboratory, Argonne, Illinois, Vitaly L. Ginzburg (87), of the P.N. Lebedev Physical Institute, Moscow, Russia, and British-born Anthony J. Leggett (65), of the University of Illinois, Urbana-Champaign, Illinois, for their work on the theory of superconductors and superfluids.

Superconducting materials are the key to magnetic resonance imaging instruments for medical examination and particle accelerators in physics. A clearer understanding of the strange properties of superfluids is also providing science with deep insights into the nature of matter.

Anthony Leggett (Credit: Photo by Bill Wiegand)

A few degrees above the super chilly absolute zero, certain materials will carry an electric current with zero resistance and displace a magnetic field. Superconductivity has been known for decades. Understanding how this effect arises has remained an enigma for physicists. Type I superconductors, those that displace magnetic fields completely, were explained by the winners of the Nobel Prize for Physics in 1972. The so-called BCS theory, successful for type-I materials was, however, left out in the cold with the discovery of the high-temperature superconductors that have emerged as the technically more important class of materials. Type-II superconductors allow superconductivity and magnetism to exist at the same time and remain superconductive in high magnetic fields.

By building on an alternative theory of type-I materials developed by Vitaly Ginzburg and others, Abrikosov was ultimately successful in explaining the type-II phenomenon. Intriguingly, the new theories were actually developed in the 1950s by these scientists. Although these theories were formulated in the 1950s, they have gained renewed importance in the rapid development of materials with completely new properties. Materials can now be made superconductive at increasingly high temperatures and strong magnetic fields, two important properties for making more sensitive instruments with greater cost-effectiveness.

Alexei Abrikosov

The third part of the Physics Nobel recognises the strange world of liquid ³helium. Below a critical temperature this material becomes a superfluid, its viscosity vanishes and it becomes essentially impossible to stir. For this unique state of matter to manifest itself, atoms of the rare helium isotope ³He have to form pairs. This is analogous to the pairing up of electrons that takes place in metallic superconductors.

The decisive theory that explains exactly how the ³He atoms interact was formulated in the 1970s by Leggett. Recent studies have shown how this order passes into chaos or turbulence, which is one of the unsolved problems of classical physics.

Category: Chemistry

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