Control of the Magneto-optical effect by spin-chirality in multiferroic magnet

近年来，非空间反演对称自旋系统中的磁光效应，如磁手性效应，引起了人们的广泛关注。在本研究中，我们尝试观察了空间反演对称性被自旋排列打破的磁电畴。我们成功地可视化了（Cu,Ni） B2O4的磁电畴，它是一种没有空间反演对称性的弱铁磁体。我们还可视化了两相共存状态，其中具有自旋手性的畴和具有共线自旋排列的畴存在，通过每个畴的光吸收的差异。

Recently, the magneto-optical effect, such as magneto-chiral effect in the spin systems without space-inversion symmetry, has been attracting much attention. In this study, we have tried to observe the magnetoelectric domain, in which the space-inversion symmetry is broken by the spin arrangement. We have succeeded to visualize the magnetoelectric domain in (Cu,Ni) B2O4, which is the weak ferromagnet without space-inversion symmetry. We have also visualized the two-phase coexisting state, in which the domain with spin chirality and that with the collinear spin arrangement exist, through the difference of the optical absorption of each domain.