Frustrated Magnetism in Novel M-Type Hexaferrites and Breathing-Pyrochlore Intermetallics

One of the most common origins for frustrated magnetism is geometric frustration of magnetic species, including triangular, Kagome and pyrochlore lattices. Here we present two new materials, i.e., a M-type hexaferrite and a breathing-pyrochlore-based intermetallc compound, which possess magnetic frustration. Due to the highly frustrated lattices on the B site of M-type hexaferrites (AB₁₂O₁₉) including triangular and Kagome sublattices, magnetic frustration is expected to appear in this system. However, only a few systems were reported to host spin-glass state due to the extensive B site disorder. We successfully synthesized the first Mn-based M-type hexaferrite, ASb3Mn9O19 (A = K, Rb), and determined the existence of frustrated magnetism in the new compounds. On the other hand, the relationship between localized electrons, itinerant electrons and frustrated magnetism has been a great challenge in the community. Here we discovered a new itinerant material with breathing pyrochlore lattice of Mo. Interestingly, the new material exhibits strongly correlated nature as well as magnetic frustration. In a word, our discoveries provide promising systems for future frustrated magnetism research in both insulating and metallic systems.