Anomalous reduced sound velocity of multiferroic TbMn2O5

作者：Cao Xian-Sheng^*

来源：Chinese Journal of Physics, 2018, 56(2): 520-524.

DOI：10.1016/j.cjph.2018.01.012

• Reduced sound velocity
• Anharmonic phonon-phonon interaction
• Multiferroic TbMn2O5

The anomalous reduced sound velocity of multiferroic TbMn2O5 (TMO) has been studied using Green's function technique. To achieve this aim, the anharmonic phonon-phonon interaction and the spin-phonon interaction were used. It was shown that the reduced velocity of sound of TMO exhibits a kink at the ferroelectric phase transition temperature T-C. This can be explained as an effect of vanishing ferroelectric ordering above T-C. It was found that the reduced sound velocity increases with increasing V-(3) (the third-order atomic force constants of the anharmonic phonons) in the interval T < T-C, whereas the reduced sound velocity remains unchanged in the interval T-C < T < T-N. It was also found that the reduced sound velocity increases with the increase of V-(4) (the fourth-order atomic force constants of the anharmonic phonons) in the interval T < T-N. In addition, the ferroelectric phase transition temperature T-C decreases when V-(4) increases in the interval T < T-N. Those theoretical results are in agreement with the experimental data.

• 出版日期2018-4
• 单位常州大学