Interplay of S = 5 / 2 spin-tetramer cluster magnetism and magnetodielectric effect in polar Ba 6 Nd 2 Fe 4 O 15

Cluster magnetism has emerged as a fertile platform for exploring unconventional magnetic and dielectric phenomena in complex oxides. In the polar compound Ba${}₆$Nd${}₂$Fe${}₄$O${}₁₅$, a detailed examination of temperature- and field-dependent magnetic, thermal, and dielectric properties reveals a distinct field-induced transition from an antiferromagnetic to a ferrimagnetic phase, accompanied by pronounced magnetodielectric coupling. The study establishes a direct connection between spin tetramer interactions and lattice polarization, demonstrating how localized spin clusters mediate strong cross-correlations between electric and magnetic orders. These results deepen the understanding of cluster-based magnetodielectric phenomena and their microscopic origins in polar magnetic oxides.