Department of Applied Physics and Quantum Phase Electronics Center (QPEC), University of Tokyo, Tokyo 113-8656, Japan.
Phys Rev Lett. 2013 Jul 19;111(3):037204. doi: 10.1103/PhysRevLett.111.037204. Epub 2013 Jul 17.
Both electric- and magnetic-dipole active spin excitations, i.e., electromagnons, which mediate the dynamical magnetoelectric effect, have been investigated for a multiferroic perovskite of manganite by optical spectroscopy at terahertz frequencies. Upon the magnetoelectric resonance at 1 meV in the multiferroic phase with the bc-plane spin cycloidal order, a gigantic dynamical magnetoelectric effect has been observed as a nonreciprocal directional dichroism or birefringence. The light k-vector-dependent difference (Δκ=κ(+)-κ(-)) of the extinction coefficient (κ(±)) is as large as Δκ1 or 2Δκ/(κ(+)+κ(-))0.7 at the lowest-lying electromagnon energy. We clarified the mutual coupling of the E(ω)[parallel]a-polarized electromagnons of the different origins, leading to the enhancement of the magnetoelectric resonance.
通过太赫兹频率的光学光谱学，研究了介电动-和磁偶极子主动自旋激发，即电磁子，它们介导动态磁电效应。在具有 bc 平面自旋旋轨序的多铁钙钛矿的铁电相中，在 1 meV 的磁电共振处，观察到作为非互易方向二色性或双折射的巨大动态磁电效应。消光系数（κ(±)）的光 k 矢量相关差（Δκ=κ(+)-κ(-)）在最低的电磁子能量下大到 Δκ1 或 2Δκ/(κ(+)+κ(-))0.7。我们澄清了不同起源的 E(ω)[平行]a 极化电磁子的相互耦合，导致磁电共振的增强。
