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Phys. Rev. Lett. 87, 037001 (2001) [4 pages]

Giant Anharmonicity and Nonlinear Electron-Phonon Coupling in MgB2: A Combined First-Principles Calculation and Neutron Scattering Study

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T. Yildirim1, O. Gülseren1,2, J. W. Lynn1, C. M. Brown1,3, T. J. Udovic1, Q. Huang1,3, N. Rogado4, K. A. Regan4, M. A. Hayward4, J. S. Slusky4, T. He4, M. K. Haas4, P. Khalifah4, K. Inumaru4, and R. J. Cava4
1NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899
2Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104
3University of Maryland, College Park, Maryland 20742
4Department of Chemistry and Princeton Materials Institute, Princeton University, Princeton, New Jersey 08544

Received 22 March 2001; published 26 June 2001

See accompanying Physics Focus

First-principles calculations of the electronic band structure and lattice dynamics for the new superconductor MgB2 are carried out and found to be in excellent agreement with our inelastic neutron scattering measurements. The numerical results reveal that the E2g in-plane boron phonons near the zone center are very anharmonic and strongly coupled to the planar B σ bands near the Fermi level. This giant anharmonicity and nonlinear electron-phonon coupling is key to quantitatively explaining the observed high Tc and boron isotope effect in MgB2.

© 2001 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevLett.87.037001
DOI:
10.1103/PhysRevLett.87.037001
PACS:
74.70.Ad, 61.12.-q, 74.25.Jb, 74.25.Kc
 
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