Evidences for local non-centrosymmetricity and strong phonon anomaly in EuCuAs: a Raman spectroscopy and lattice dynamics study.

Phonon modes and their association with the electronic states have been investigated for the metallic EuCuAssystem. In this work, we present the Raman spectra of this pnictide system which clearly shows the presence of seven well defined peaks above 100 cmthat is consistent with the locally non-centrosymmetriccrystal structure, contrary to that what is expected from the accepted symmorphicstructure. Lattice dynamics calculations using thesymmetry attest that there is a commendable agreement between the calculated phonon spectra at the Γ point and the observed Raman mode frequencies, with the most intense peak at∼232 cmbeing ascribed to the A1gmode.