Leggett, Anthony James (1938-…), a British and American physicist, won a share of the 2003 Nobel Prize in physics for his research on superfluids, fluids that flow absolutely freely. The prize was also awarded to the Soviet-born physicist Alexei A. Abrikosov and the Russian physicist Vitaly L. Ginzburg.
Leggett won the Nobel Prize for research he conducted at the University of Sussex, in England, during the 1970’s. Leggett studied a rare isotope (form) of helium called helium 3. Like helium 4, the most common isotope of helium, helium 3 becomes a superfluid at extremely low temperatures. At those temperatures, both liquids exhibit strange behavior, such as the ability to flow through tiny cracks and to “crawl” up the sides of a container. See Superfluid .
Helium 3, however, has several unique qualities. Helium 4, for example, becomes a superfluid within a few degrees of absolute zero (-459.67 °F or -273.15 °C). Helium 3, however, must be lowered to about .0016 Fahrenheit degree (.0009 Celsius degree) above absolute zero to become a superfluid. Also, superfluid helium 4 is isotropic—that is, it has the same magnetic and electric properties in all directions. Helium 3, on the other hand, is anisotropic, meaning it has different magnetic and electric properties when scientists measure it in different directions.
Leggett developed a theory to explain how these differences resulted from differences in the structures of the two superfluids. Although atoms of superfluid helium 4 move separately, Leggett theorized that superfluid helium 3 atoms join together in pairs. In each pair, the electric and magnetic properties of the two atoms interact, giving superfluid helium 3 its unique qualities. Leggett used his theory to develop mathematical models to predict and describe the behavior of superfluid helium 3. Later experiments confirmed his theory.
Leggett also studied other strange behaviors that occur at extremely low temperatures. He studied superconductivity, the ability of some substances to conduct electric current without resistance, and Bose-Einstein condensation, the ability of a cloud of atoms to act as a single atom.
Leggett was born in London on March 26, 1938. He received a Ph.D. degree in theoretical physics from Oxford University in 1964. From 1978 to 1983, Leggett worked as a professor at the University of Sussex. In 1983, he became a professor at the University of Illinois in Urbana-Champaign. Leggett became a U.S. citizen in 2001 and also kept his British citizenship.
