Electromagnon and phonon excitations in multiferroic TbMnO3

Abstract

We have performed Raman measurements on TbMnO3 single crystal under magnetic field along the three crystallographic directions. The flip of the spin spiral plane creates an electromagnon excitation. In addition to the electromagnons induced by the Heisenberg coupling, we have detected the electromagnon created by the Dzyaloshinskii-Moriya interaction along the c axis. We have identified all the vibrational modes of TbMnO3. Their temperature dependences show that only one phonon observed along the polarization axis is sensitive to the ferroelectric transition. This mode is tied to the Tb 3+ ion displacements that contribute to the ferroelectric polarization.

A comparative Raman study between PrMnO 3, NdMnO 3, TbMnO 3 and DyMnO 3

“…The frequencies of the A g and B 1 g Raman active phonons of PrMnO 3 , NdMnO 3 , TbMnO 3 and DyMnO 3 are reported in Table 1. Their vibrational characters are assigned in agreement with previous Raman measurements 29 . With decreasing the ionic radius of R ( r Pr > r Nd > r Tb > r Dy ) most phonon frequencies shift towards higher values.…”

Optically probed symmetry breaking in the chiral magnetCu2OSeO3

“…8,9 Effects on the optical properties have been studied extensively. [10][11][12] One intriguing optical phenomenon originating from the combined absence of time-reversal and space-inversion symmetry is the so-called nonreciprocal directional dichroism. [13][14][15] The high sensitivity of optical properties to symmetry breaking may be used to gain a better understanding of the underlying material properties.…”

Impact of temperature-dependent local and global spin order inRMnO3compounds for spin–phonon coupling and electromagnon activity

“…Besides, we want to point out that the Raman data of several other research groups show SPC at  T T N generally for RMnO 3 compounds, e.g. for DyMnO 3 with = T 40 N K and » T 120 SPC K [32] and several others [32,42,43], but in none of these reports this observation is discussed in terms of Mn-spin order in this temperature range. In our opinion all existing results on the temperature dependence of SPC in RMnO 3 can be explained consistently by assuming a that this SPC is due to local, short-range order of the Mn spins, persisting far above the Néel temperature.…”