[8p-E217-1~15] 9.5 New functional materials and new phenomena

2:15 PM - 2:30 PM JST(5:15 AM - 5:30 AM UTC)Presentation by Applicant for JSAP Young Scientists Presentation Award

[8p-E217-4] Tuning of Fe₄O₁₅ cluster magnetism by chemical substitution for Ba₆La₂Fe₄O₁₅

〇(D)Takumi Shirasaki¹, Taro Matsuzawa¹, Taichi Ishikawa¹, Hideki Kuwahara¹ (1.Sophia Univ.)

Keywords:

cluster magnetism,multiferroics,3d transition metal

Polar magnets with broken inversion symmetry in the paramagnetic phase are promising hosts for large magnetoelectric effects. Ba₆La₂Fe₄O₁₅ is the new polar magnet contain Fe₄O₁₅ clusters. Intra-cluster superexchange interactions bind the four Fe³⁺ (S = 5/2) spins into a total spin S_T = 5, giving a cluster-paramagnetic state that hosts a magnetoelectric effect. To clarify how the electronic state governs this cluster magnetism, we synthesized the solid solution Ba₆La₂(Fe_1-xCo_x)₄O₁₅. The Fe end member orders antiferromagnetically at T_N = 12.8 K, whereas the Co end member shows a spin-glass transition at T_SG = 62 K. This indicates a low-spin Co³⁺ that quenches the intra-cluster superexchange interactions, leading to the collapse of the total spin. Cluster magnetism is thus tunable via electronic configuration and site occupancy of the substituent ions.