Phonons in MgB2 by polarized Raman scattering on single crystals - art. no. 140503

This paper presents a detailed Raman scattering study of the unusually broa d E-2g phonon mode in MgB2 crystal. It is shown by polarized Raman scatteri ng on a few-micron-size crystallites with natural faces that the observed b road Raman feature really does obey the selection rules of an E-2g mode. Ra man spectra on high quality polycrystalline superconducting MgB2 wires reve al a very symmetric E-2g phonon line near 615 cm(-1) with the room temperat ure linewidth of 260 cm(-1) only. Additional scattering of different polari zation dependence, observed in certain crystallites, is interpreted as weig hted phonon density of states induced by lattice imperfections.