Local symmetry breaking in Eu1-xLaxB6

Abstract

We report inelastic light (Raman) scattering study of Eu1-xLaxB6 (x = 0, 0.05, 0.1, 0.2, 0.3). As La is doped, the T-2g mode becomes broad and asymmetric, the E-g mode splits into doublet, and the A(1g) mode shifts to higher frequencies, while the undoped EuB6 show sharp three phonon peaks, T-2g, E-g, and A(1g) modes. There are around six possible phonon peaks in the Raman spectra of La-doped EuB6. These additional peaks are explained by symmetry lowering of boron octahedra due to tilting/rotating. (c) 2006 Published by Elsevier B.V.