The Raman spectrum of Ba2CuGe2O7, a tetragonal insulator which develops Dzyaloshinskii-Moriya helical magnetism below TN = 3.2 K, has been detected at temperatures varying from 300 to 80 K in a single crystal, with the radiation polarized either in the ab plane or along the c axis of its tetragonal cell. Twenty-nine phonon lines out of the 35 allowed by ... إقراء المزيد