Superconductivity of MgB2: covalent bonds driven metallic.
By J. An, W. Pickett. Physical Review Letters, 2001
623 citations recorded by the source corpus.
A series of calculations on MgB2 and related isoelectronic systems indicates that the layer of Mg2+ ions lowers the nonbonding B pi ( p(z)) bands relative to the bonding sigma ( sp(x)p(y)) bands compared to graphite, causing sigma-->pi charge transfer and sigma band doping of 0.13 holes/cell. Because of their two dimensionality the sigma bands contribute strongly to the Fermi level density of states. Calculated deformation potentials of gamma point phonons identify the B bond stretching modes as dominating the electron-phonon coupling. Superconductivity driven by sigma band holes is consistent with the report of destruction of superconductivity by doping with Al.
Subfields: Condensed Matter Physics, Materials Chemistry
View Paper: https://www.semanticscholar.org/paper/ab0dcce930533f4157ebbbfe38540acc9f1d26ba
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In Condensed Matter Physics
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Citations in the corpus
- Two-band superconductor magnesium diboride (2008, background): “px,y orbital overlap; therefore the electron–phonon coupling between the E2g mode and the σ band is very strong [8, 9, 101].”
- A perspective on conventional high-temperature superconductors at high pressure: Methods and materials (2019, background): “Being formed by magnesium and boron, two of the lightest elements of the periodic table, MgB2 was a rare example of covalent metal [35] in which (relatively) high-Tc superconductivity could be obtained exploiting high phonon frequencies and large electron-phonon matrix elements.”
- Very high upper critical fields in MgB2 produced by selective tuning of impurity scattering (2003, result): “For instance, ab initio calculations for clean MgB2 single crystals [39, 40 ] have shown that the ratio of the averaged squared Fermi velocities, � v2 ab� σ /� v 2 c � σ ≈ 46, for the σ band is much higher than � v2ab� π /� v 2 c � π ≈”