Applied Physics

Scaling Superconductive Memories

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Science  03 Nov 2006:
Vol. 314, Issue 5800, pp. 729
DOI: 10.1126/science.314.5800.729c

Superconducting electronic systems offer great potential to improve the speed of conventional computers through low power dissipation and switching times on the order of picoseconds. One problem, however, has been to develop small-sized memory storage elements that are also compatible with large-scale integration. For instance, data storage in these systems has generally been based on harboring magnetic flux in a superconducting loop, and those loops tend to be several micrometers in diameter.

Held et al. propose the design of a memory element based on a ferromagnetic dot coupled to a superconducting Josephson junction. Because the critical current of a Josephson junction is magnetic field-dependent, the magnetization of the dot can be switched to modulate the field in the junction either below or above a critical value. The data, 0 or 1, are thus stored as the magnetization direction in the dot and can be read out as the critical current of the Josephson junction. Preliminary experiments using a Permalloy (Ni81Fe19) dot demonstrate the principle of operation and also show nonvolatile storage capability at room temperature. The authors note that optimization of the device should reduce the relatively high (∼100 mA) applied currents required to switch the dot magnetization. — ISO

Appl. Phys. Lett. 89, 163509 (2006).

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