Applied Physics

Turning On (and Off) Superconductivity

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Science  28 Apr 2000:
Vol. 288, Issue 5466, pp. 577
DOI: 10.1126/science.288.5466.577a

Superconducting switching devices offer the potential of processing speeds and low power dissipation inaccessible to conventional microelectronics (see also Schön et al., Reports, this issue, p. 656). So far, however, the devices have been relatively large and the switching circuitry too unwieldy for high-density integration.

Clinton and Johnson have developed a magnetic superconducting valve (MSV) with a simplified design in which the magnetization orientations of the ferromagnetic layers in a magnetically coupled bilayer sitting atop a thin lead film determine whether the thin film is superconducting. When the magnetizations in the bilayer are parallel, the high magnetic fringe fields developed at the lower ferromagnetic layer penetrate into the lead film and are large enough to destroy superconductivity. Switching the magnetization in the upper ferromagnetic material to an anti-parallel orientation pulls the fringe fields into the top layer, leaving the superconducting film undisturbed. The architecture introduced here should allow for the development of high-density superconducting memory devices.—ISO

Appl. Phys. Lett.76, 2116 (2000).

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