Raman phonon spectrum of the Dzyaloshinskii-Moriya helimagnet Ba2CuGe2O7 (art: PRB 91, 214308)

F. CAPITANI; S. KOVAL; R. FITTIPALDI; S. CARAMAZZA; E. PARIS; W. S. MOHAMED; J. LORENZANA; A. NUCARA; L. ROCCO; A. VECCHIONE; P. POSTORINO; P. CALVANI

PHYSICAL REVIEW B

AMER PHYSICAL SOC

Lugar: New York; Año: 2015 vol. 91 p. 214308 - 2143013

1098-0121

The Raman spectrum of Ba2CuGe2O7 , a tetragonal insulator which develops Dzyaloshinskii-Moriya helicalmagnetism below T N = 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 phononlines out of the 35 allowed by the Raman selection rules for the present geometry were observed, and theirvibrational frequencies were found in overall good agreement with those provided by shell-model calculations.Together with the previous report on the infrared-active phonons [A. Nucara et al., Phys. Rev. B 90, 014304(2014)], the present study provides an exhaustive description, both experimental and theoretical, of the latticedynamics in Ba2CuGe2O7 .