Ab Initio Investigation of Collective Charge Excitations in MgB_2

Wei Ku; W. E. Pickett; R. T. Scalettar; A. G. Eguiluz

doi:10.1103/physrevlett.88.057001

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Ab Initio Investigation of Collective Charge Excitations in MgB_2

Wei Ku·W. E. Pickett·R. T. Scalettar·A. G. Eguiluz

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Abstract

A sharp collective charge excitation is predicted in MgB$_2$ at $\sim2.5eV$ for $q$ perpendicular to the boron layers, based on an all-electron analysis of the dynamical density response within time-dependent density functional theory. This novel excitation, consisting of coherent charge fluctuation between Mg and B sheets, induces an abrupt plasma edge in the experimentally-observable reflectivity. The existence of this mode reflects the unique electronic structure of MgB$_2$, that is also responsible for strong electron-phonon coupling. By contrast, the acoustic plasmon, recently suggested to explain the high $T_c$, is not realized when realistic transition strengths are incorporated.

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Wei Ku, W. E. Pickett, R. T. Scalettar, A. G. Eguiluz. 2001-12-07. Ab Initio Investigation of Collective Charge Excitations in MgB_2. https://doi.org/10.1103/physrevlett.88.057001

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