Nanoscale Superconductivity: Potential Energy Source

At the University of Alberta, Dr Frank Marsiglio is pushing the limits of nanoscale systems research. His present research focuses on understanding superconductor systems and their applicability in nanograin superconductivity.

Historically, superconductivity research has been based on foundations of grand canonical ensembles generating approximate results with relative margins of error. Today, the forward thrust of miniaturization has created a new challenge in solving the problem of marginal errors, as current experiments detect the difference between even and odd numbers of electrons in ultra small superconducting grains.

In response to this problem Marsiglio has reformulated superconductivity equations providing precise values with no margin of error. This development enables the proper description of superconductivity in small nanograins providing a correct description of surfaces and impurities. Marsiglio’s research has also taken into account the order parameter and spatial dependence. Thus, even the occurrence of surfaces results in a dramatic change in the order parameter particularly in the case where the order parameter has d-wave symmetry.

MACI has played an integral part in this nanoscale research. Having the ability to solve tens of thousands of coupled equations is imperative for first-rate results and developments. As the ability to fabricate small superconducting nanograins improves, and probes for observing the effect of superconductivity in these grains improve in resolution, continued computational infrastructure is a necessity to enable the theory to be capable of critically examining fascinating properties of nanograins.

Such formalism is essential to properly describe the results of surface-sensitive probes of the high temperature superconductors. The impact of this formalization will continue to influence STM work and photoemission spectroscopy. Potential ramifications include miniaturization of superconducting components, and interfacing with superconducting surfaces on mixed (superconducting and semiconducting) components.

Selected Publications

K. Beach, R. Gooding, F. Marsiglio. Feedback effects and the Self-Consistent Thouless Criterion of the Attractive Hubbard Model, accepted for publication, Phys. Lett. A, March 2001.

K. Tanaka and F. Marsiglio. Possible Electronic Shell Structure of Nanoscale Superconductors, Phys. Lett. A, 265, 133-138, 2000.

K. Tanaka and F. Marsiglio. The Anderson Prescription for Surfaces and Impurities, Phys. Rev. B, 62, 5345-5348, 2000.

 K. Tanaka and F. Marsiglio. Even-odd and super-even effects in the attractive Hubbard model, Phys. Rev. B 60, 3508-3526, 1999.

K. Tanaka and F. Marsiglio. Anderson's "Theorem" and Bogoliubov-de Gennes Equations for Surfaces and Impurities, To be published in Physica C, 6th International Conference on Materials and Mechanisms of Superconductivity, Houston, February 2000.