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Research Area Summary:
Superconducting materials are used in a wide variety of defense and
civilian technologies. Navy applications include superconducting
motors for electric drives, microwave devices, superconducting magnets
and mine sweeping.
 | FIG. 1.
The imaginary (a) and the real (b)
parts of the calculated non-interacting spin ssusceptibility
of LaFeAsO1-xFx.
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The Center for Computational Materials Science has
a long history of supporting the Navy's interest in superconducting
materials. First principles calculations were used, starting in the
mid-1970's, to calculate the electron-phonon interactions in elemental
metals, carbides, nitrides, hydrides and the A15 compounds. The goals
of the work were to advance understanding of the microscopic basis of
superconductivity, to establish a predictive first principles
framework for the investigation of superconducting materials, and to
identify new phases with potentially high critical temperatures, for
experimental investigation.
Recent work in the Center is continuing this line of research by applying
modern linear-response methods combined with numerical solvers for the
Eliashberg equations to address electron-phonon
mediated superconductivity, especially in novel materials such as
MgB2 or CaC6. This has resulted in a new understanding of
the materials -- for example, the prediction of two-gap
superconductivity in MgB2 -- as well as suggestions for
improved materials -- for example, the prediction of still higher
critical temperatures in the as yet unsynthesized compound,
Li2B2-xCx. The Center also has a
significant effort investigating materials with both magnetism and
superconductivity, particularly unconventional
superconductivity mediated by spin fluctuations, as in
Sr2RuO4,
NaxCoO2.yH2O, and the newly discovered
ferropnictides.
Further Reading:
- Unconventional
Superconductivity with a Sign Reversal in the Order Parameter of
LaFeAsO1-xFx
I. I. Mazin, D. J. Singh, M. D. Johannes, and M. H. Du, Phys. Rev. Lett 101, 057003 (2008)
- A critical assessment of the superconducting pairing symmetry in NaxCoO2.yH2O ,
I. I. Mazin and M. D. Johannes, Nature Pphysics 1, 91 (2005)
- Intercalant-driven superconductivity in YbC6 and CaC6, I.I. Mazin, Phys. Rev. Lett. 95, 227001 (2005)
- Critical temperature and enhanced isotope effect in the presence of paramagnons in phonon-mediated superconductors
, O. V. Dolgov, I. I. Mazin, A. A. Golubov, S. Y. Savrasov, and E. G. Maksimov, Phys. Rev. Lett. 95, 27003 (2005)
- Phase-Sensitive Tests of the Pairing State Symmetry in Sr2RuO4
, Igor Zutic and Igor Mazin, Phys. Rev. Lett. 95, 217004 (2005)
Point of contact:
Igor.Mazin@nrl.navy.mil
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