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In October, the 1996 Nobel Prize in Physics was awarded to David Lee and Robert Richardson of Cornell University and Douglas Osheroff of Stanford University for their 1972 discovery of superfluidity in helium-3. This special liquid state of matter, which can flow without viscosity, was detected during a search for an antiferromagnetic phase in solid He-3, after the researchers chilled their sample to a temperature of about 2 microkelvins. Superfluidity was discovered in helium-4 in 1938, at the much warmer temperature of 2 kelvin.
Superfluidity in He-3 is very different from He-4. For instance, the former is a fermion and the latter is a boson. And in He-4, the superfluid state is essentially a Bose-Einstein condensation of He atoms in a single quantum state, whereas the He-3 superfluid state is a condensation of pairs of atoms, which are magnetic and possess an internal structure. In fact, superfluid He-3 exists in three different phases related to different magnetic or temperature conditions. The highly anisotropic nature of the A phase (resembling a liquid crystal) was recently exploited in an experiment in which vortices set in motion within an He-3 sample simulated the formation of topological defects, or "cosmic strings," in the early universe. [See Nature, 25 July 1996]
A graduate student at Cornell when the discovery was made, Osheroff went on to achieve the first experimental verification of the "baked Alaska" model, a theory first formulated by Anthony Leggett (University of Illinois) to explain the somewhat piecemeal transition from the A phase of superfluid He-3 into the lower-temperature B phase, by supposing that B-phase droplets can be nucleated within the supercooled A phase by the ionizing energy of passing cosmic rays. [See Physics Today, June 1992]
The 1996 Nobel Prize in Chemistry was shared by Richard F. Curl and Richard E. Smalley of Rice University, along with Harold W. Kroto of the University of Sussex, for their 1985 discovery of fullerenes, new forms of carbon that include the soccer-ball shaped carbon-60 atoms otherwise known as "buckyballs", because their shape resembles the geodesic domes pioneered by the architect Buckminster Fuller.
Lee, Richardson and Osheroff are APS Fellows and were awarded the APS Oliver E. Buckley Prize in 1981 for their discovery. Smalley, who is also an APS Fellow, was similarly honored in 1991 with the APS Irving Langmuir Prize in Chemical Physics. In addition, Richardson is a former chair of the APS Division of Condensed Matter Physics, and Osheroff has been active in numerous APS activities.
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