[22p-E205-1~16] 10.1 新物質・新機能創成（作製・評価技術）

▲ [22p-E205-16] Engineering 180 degree magnetoelectric switching phenomena and enhanced magnetization in hexagonal ferrites through carrier doping

〇Hena Das^1,2 (1.Laboratory for Materials and Structures, Tokyo Institute of Technology、2.Tokyo Tech World Research Hub Initiative (WRHI), Institute of Innovative Research, Tokyo Institute of Technology)

キーワード：Computational materials physics, magnetoelectrics, ferroelectrics, frustrated magnets, non-trivial topological phenomena

The quest for magnetoelectric switching mechanisms of controlling magnetic order in systems by the application of electric fields, is an active area of research. In this regard LuFeO₃ type hexagonal oxides hold immense potential as working materials. LuFeO₃ forms an improper ferroelectric order below ~ 1020 K with a robust electric polarization and a canted antiferromagnetic order below 147 K, exhibiting a weak magnetization ~ 0.03 μ_B/Fe. A cross coupling between ferroelectric and magnetic order in LuFeO₃ type hexagonal systems was proposed by leveraging the cross coupling between non-polar trimer distortions (Q_K3) and anti-symmetric exchange interactions between Fe⁺³ (S=5/2) magnetic ions. In the present study, we report a 180 degree magnetoelectric switching mechanism driven by the complex mutual interaction of the multiple magnetic sublattices created within this hexagonal lattice and their evolution and subsequent behavior under the effect of trimer distortions Q_K3. A situation like this can be effected by doping LuFeO₃ with carriers. We conceptualized the proposed ME coupling for a doping concentration of 1/3 electrons per Fe. The localization of the doped carriers introduces S=2 magnetic site within a S=5/2 hexagon. Here, we have identified three different magnetic phases and have showed that the transformation of one phase to another strongly depends on the temperature and Q_K3. In these magnetic phases the spin orientation of the S=2 sublattice is perpendicular to that of the S=5/2 sublattice. This mutually influencing orientation is driven by the Dzyaloshinskii-Moriya (DM) interactions between two sublattices, resulting not only in an enhancement of the net magnetization by order of magnitude, but also in an increase of the magnetic transition temperature compared to the parent system.