Superconductivity of metallic boron in MgB2.
Boron in MgB2 forms stacks of honeycomb layers with magnesium as a space filler. Band structure calculations indicate that Mg is substantially ionized, and the bands at the Fermi level derive mainly from B orbitals. Strong bonding with an ionic component and considerable metallic density of states yield a sizable electron-phonon coupling. Together with high phonon frequencies, which we estimate via zone-center frozen phonon calculations to be between 300 and 700 cm(-1), this produces a high critical temperature, consistent with recent experiments. Thus MgB2 can be viewed as an analog of the long sought, but still hypothetical, superconducting metallic hydrogen.
Kortus
J
J
Georgetown University, Washington, D.C. 20057 and Center for Computational Materials Science, Code 6390, Naval Research Laboratory, Washington, D.C. 20375.
Mazin
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Belashchenko
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Antropov
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Boyer
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