Fabrication and characterization of nanostructured Fe₃S₄, an isostructural compound of half-metallic Fe₃O₄

High-purity, well-crystallized spinel Fe₃S₄ nanoplatelets were synthesized by the hydrothermal method, and the saturation magnetic moment of Fe₃S₄ was measured at 1.83 μ_Bf.u. The temperature-dependent resistivity of Fe₃S₄ was metallic-like for T < 180 K: room-temperature resistivity was measured at 7.711 × 10³μΩ cm. The anomalous Hall conductivity of Fe₃S₄ decreased with increasing longitudinal conductivity, in sharp contrast with the accepted theory of the anomalous Hall effect in a dirty-metal regime. Furthermore, negligible spin-dependent magnetoresistance was observed. Band structure calculations confirmed our experimental observations that Fe₃S₄ is a metal and not a half metal as expected.