Raman scattering from a superconductivity-induced bound state in Mg B 2
Abstract
It is shown that the sharp peak in the
E
2g
Raman spectrum of superconducting
Mg
B
2
is due to a bound state caused by the electron-phonon coupling. Our theory explains why this peak appears only in the spectra with
E
2g
symmetry and only in the
σ
but not
π
bands. The properties of the bound state and the Raman spectrum are investigated, also in the presence of impurity scattering.