Abstract-Electric field control of terahertz polarization in a multiferroic manganite with electromagnons

A. Shuvaev, V. Dziom, Anna Pimenov, M. Schiebl, A. A. Mukhin, A. Komarek, T. Finger, M. Braden, A. Pimenov

(Submitted on 5 Apr 2017)

https://arxiv.org/abs/1704.01498

All-electrical control of a dynamic magnetoelectric effect is demonstrated in a classical multiferroic manganite DyMnO3, a material containing coupled antiferromagnetic and ferroelectric orders. Due to intrinsic magnetoelectric coupling with electromagnons a linearly polarized terahertz light rotates upon passing through the sample. The amplitude and the direction of the polarization rotation are defined by the orientation of ferroelectric domains and can be switched by static voltage. These experiments allow the terahertz polarization to be tuned using the dynamic magnetoelectric effect.

Abstract-Terahertz spectroscopy of crystal-field transitions in magnetoelectric TmAl3(BO3)4

A. M. Kuzmenko, A. A. Mukhin, V. Vu. Ivanov, G. A. Komandin, A. Shuvaev, A. Pimenov, V. Dziom, L. N. Bezmaternykh, I. A. Gudim

(Submitted on 7 Apr 2017)

https://arxiv.org/abs/1704.02198

Dynamic magnetic properties of magnetoelectric TmAl3(BO3)4 borate have been investigated by terahertz spectroscopy. Crystal field (CF) transitions within the ground multiplet 3H6 of Tm3+ ions are observed and they are identified as magnetic-dipole transitions from the ground singlet A1 to the next excited doublet E of Tm3+ ions. Unexpected fine structure of the transitions is detected at low temperatures. The new modes are assigned to local distortions of the sites with D3 symmetry by Bi3+ impurities, which resulted in the splitting of A1 -> E transition. Two types of locally distorted sites are identified and investigated. The main contribution to the static magnetic susceptibility is shown to be determined by the matrix elements of the observed magnetic transitions. We demonstrate that even in case of local distortions the symmetry of the undistorted crystal is recovered for magnetic and for quadratic magnetoelectric susceptibilities.