Observation of Magnetoelectric Directional Anisotropy

Abstract

We report the first observation of a new optical phenomenon, magnetoelectric directional anisotropy (MEA). MEA is a polarization-independent anisotropy which occurs in crossed electric field E and magnetic field B perpendicular to the wave vector k of the light. It is described by a contribution to the refractive index of the form (delta)n=(gamma)k x E x B. Our experiment was performed on a Er(1.5)Y(1.5)Al(5)O(12) crystal, but MEA should exist in all media. The relation of this new effect with recently discovered magnetoelectric birefringence is discussed.

Momentum Transfer from Quantum Vacuum to Magnetoelectric Matter

“…Optical ME effects have been observed in birefringence [8][9][10] and in absorption [11][12][13]. The final result of Ref.…”

Microwave Magnetochiral Effect inCu2OSeO3

“…Indeed observations of the directional dichroism have been reported for several multiferroic materials such as Ba 2 CoGe 2 O 7 [17][18][19], RMnO 3 (R =rare-earth ions) [20,21], and CuFe 1−x Ga x O 2 [22], in which nontrivial spin orders induce the ferroelectric polarization via the relativistic spin-orbit interaction. In these materials, the optical ME effect is observed at the electromagnon resonance frequencies in the terahertz (THz) regime.The directional dichroism is observed also at higher frequencies, i.e., x-ray and visible-light regimes in several polar magnets, which is caused by electron transitions among the spin-orbit multiplets [23][24][25][26][27][28][29]. However, observations of the effect at gigahertz (GHz) frequencies are quite limited and the effect observed so far is very tiny whose difference in absorption intensity is only 2.5% at most [32], while the directional dichroism at GHz frequencies is anticipated for application to microwave devices [30].…”

“…The directional dichroism is observed also at higher frequencies, i.e., x-ray and visible-light regimes in several polar magnets, which is caused by electron transitions among the spin-orbit multiplets [23][24][25][26][27][28][29]. However, observations of the effect at gigahertz (GHz) frequencies are quite limited and the effect observed so far is very tiny whose difference in absorption intensity is only 2.5% at most [32], while the directional dichroism at GHz frequencies is anticipated for application to microwave devices [30].…”

Magnetoelectric Jones Dichroism in Atoms

“…Finally, we point out that atomic systems may be of use in measuring other types of magnetoelectric effects which are currently being studied in more complicated systems, such as more common forms of magnetoelectric linear birefringence [12] and magnetoelectric directional anisotropy [13]. In fact, expression (6) shows that this system exhibits both of these effects.…”