Investigation of the Complex Magnetic Behavior of the Spinel Material Fe₃V₃O₈

Chia-Chi Lu¹, Yu-Hsien Lin¹, Ming-Hsuan Liao¹, Yu-Ting Lee¹, Chun-Chuen Yang^2*, Yung-Hsiang Tung², Chin-Wei Wang³, Wei-Tin Chen⁴, Chien-Lung Huang⁵

¹Department of Physics, Chung Yuan Christian University, Zhongli, Taoyuan, Taiwan
²Department of Physics, National Central University, Zhongli, Taoyuan, Taiwan
³Neutron Group, National Synchrotron Radiation Research Center, Hsinchu Science Park, Hsinchu, Taiwan
⁴Center for Condensed Matter Sciences, National Taiwan University, Taipei, Taiwan
⁵Department of Physics, National Cheng Kung University, Tainan, Taiwan

* Presenter:Chun-Chuen Yang, email:chunchuenyang@ncu.edu.tw

Fe₃V₃O₈ exhibits complex magnetic behavior due to the doping of Fe ions at the A and B sites of the spinel structure. Ferromagnetic behavior begins to appear as the temperature drops from 475 K to 400 K. Above 187 K, it displays characteristics of a cluster glass-like magnetism. The magnetic susceptibility experiment shows an antiferromagnetic feature peak at 187 K. Neutron diffraction data suggest that this phenomenon arises from the Fe ions at the A and B sites producing magnetic moments of different magnitudes, leading to a ferrimagnetic property. The neutron inelastic scattering experiment reveals the presence of a 7 meV spin gap at 1.5 K. This gap is induced by the spin-orbit interaction in the divalent iron located at position A. At 3.3 K, the magnetic moments of the Fe ions at the A and B sites reach 3.25 and -1.25µB/Fe along c axis respectively, which aligns with the M-H curve results. Furthermore, the M-H curve at 2 K also reveals the formation of magnetic domains, with a coercivity of 3500 Oe.

Keywords: spinel, neutron scattering, ferrimagnetism, glass state, spin-orbit coupling