Experimental analysis shows competing mechanisms affecting conductivity in NiCo₂O₄ films, indicating new behaviors.
Room-temperature coexistence of metallic conductivity and robust perpendicular magnetic anisotropy (PMA) is vital for spintronics. We systematically investigate thickness- and temperature-dependent magnetotransport in epitaxial (001) NiCo₂O₄/MgAl₂O₄ films. Square anomalous Hall hysteresis loops persist over the entire temperature range, maintaining strong PMA at a thickness of 10 nm. Anomalous Hall conductivity (σxy) shows nonmonotonic temperature dependence, indicating competing mechanisms. Scaling analysis of σxy versus longitudinal conductivity (σxx) reveals dual contributions from intrinsic Berry curvature and extrinsic skew-scattering. The unexpected skew-scattering in this system highlights unconventional charge transport behavior in NiCo₂O₄, necessitating further study of electronic correlations and anomalous Hall effect mechanisms in oxides.
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Li et al. (2025) studied this question.