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

近年来，无空间反转对称性的自旋系统中的磁光效应，如磁手征效应，引起了人们的广泛关注。在本研究中，我们尝试观察到空间反转对称性被自旋排列破坏的磁电域。我们成功地可视化了(Cu，Ni)B2O4中的磁电畴，这是一种没有空间反转对称性的弱铁磁体。我们还通过每个磁区的光吸收的不同，可视化了具有自旋手性的磁区和具有共线自旋排列的磁区存在的两相共存状态。

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.