Spectral origin of the colossal magnetodielectric effect in multiferroic DyMn2O5

초록

The origin of the colossal magnetodielectric (CMD) effect in DyMn2O5 [N. Hur et al., Phys. Rev. Lett. 93, 107207 (2004)] has been an outstanding question in multiferroics. Here, we report the activation of the electric dipole mode at 4-5 cm(-1) in an applied magnetic field, which fully accounts for the CMD effect. We examine two alternative explanations of this mode: an electromagnon and transitions between f-electron levels of Dy3+ ions. The experimental and theoretical evidence supports an electromagnon origin of the CMD effect.