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Physics News Update
Number 313 (Story #2), March 24, 1997 by Phillip F. Schewe and Ben Stein

SINGLE MAGNETIC ATOMS DISRUPT SUPERCONDUCTIVITY on an atomic scale. As part of their microscopic study of magnetism, Ali Yazdani and his colleagues at IBM Almaden deposit single manganese (Mn) and gadolinium (Gd) atoms, each of which exerts magnetic forces, onto a niobium metal, which is a superconductor at low temperatures. By measuring the tunneling current that flows from the surface to the probe of a scanning tunneling microscope, the researchers detected the loss of superconductivity in the vicinity of the isolated magnetic atoms. This represents the first time a local loss of the superconducting state at the atomic scale has been detected. The researchers theorize that the atoms break up nearby electron pairs which constitute supercurrents. (Talk at the APS meeting; also Science, 14 March 1997; IBM Press Release, 21 March 1997.)