Number 173 (Story #2), April 12, 1994 by Phillip F. Schewe and Ben Stein IS HIGH-TEMPERATURE SUPERCONDUCTIVITY d-WAVE in nature? Low-temperature superconductivity is characterized by "s-wave" Cooper pairs. That is, supercurrent consists of pairs of electrons in composite states with zero angular momentum. By contrast, in high- temperature superconductivity, some theorists believe, the Cooper pairs are in "d-wave" states having an angular momentum of two units. At the March APS meeting in Pittsburgh, John Kirtley of IBM reported on an experiment measuring the spontaneous magnetic flux through tiny high-temperature superconducting rings. The flux equaled integral multiples of the basic unit of magnetic flux (defined as Planck's constant divided by twice the charge of the electron) when the ring consisted of one or two crystal grains. However, the measured flux proved to be only half the basic flux unit when the ring was made of three grains, a configuration which has a different quantum effect on the supercurrent as it flows around the ring than does a ring with only two grain boundaries. This half-integral flux had never been directly observed before, and the IBM scientists believe that their finding supports, but does not yet prove, the notion that the electron pairing in their high-temperature superconductor is d-wave in nature. (Science News, 2 April 1994.)