Micro-Raman and infrared studies of multiferroic TbMn₂O₅

Area of Science:

• Condensed Matter Physics
• Materials Science
• Spectroscopy

Background:

• Terbium Manganese Oxide (TbMn2O5) exhibits complex magnetic and magnetoelectric properties.
• Understanding spin-lattice coupling is crucial for developing novel multiferroic materials.

Purpose of the Study:

• To investigate the spin-lattice coupling in TbMn2O5 using Raman and infrared spectroscopy under an applied magnetic field.
• To elucidate the relationship between magnetic field, lattice vibrations, and magnetoelectric effects in TbMn2O5.

Main Methods:

• Raman spectroscopy at 4.2 K with an applied magnetic field parallel to the a-axis.
• Infrared spectroscopy at 4.2 K with an applied magnetic field parallel to the a-axis.
• Comparative analysis with Bismuth Manganese Oxide (BiMn2O5).

Main Results:

• Significant frequency shifts in Raman and infrared phonons of TbMn2O5 under magnetic field, unlike BiMn2O5.
• Phonon behavior correlated with polarization switching and exhibited softening below 3 T.
• Evidence of local lattice striction due to Tb(3+) spin alignment and charge transfer contributions to magnetoelectricity.

Conclusions:

• TbMn2O5 displays strong spin-lattice coupling, confirmed by magnetic field-dependent phonon responses.
• The observed phenomena are influenced by exchange parameters (J3 and J4) and Tb(3+) spin alignment.
• Charge transfer mechanisms play a role in the magnetoelectric properties of TbMn2O5.