Band structure of ferromagnetic Fe₄N thin-film revealed by spin- and angle- resolved photoelectron spectroscopy

Recently, transition metal binary and ternary compounds such as Fe₃Ga and Co₂MnGa have attracted new attention due to the giant anomalous Hall and Nernst effects caused by Berry curvature in their topological band structures. It has provoked a search for new materials that exhibits the great anomalous conductivity. Fe₄N is a well-known ferromagnet with an anti-perovskite structure, showing the inverse tunneling magnetoresistance and anisotropic magnetoresistance. Recently, the large anomalous Nernst coefficient has been reported. To access its origin, we have performed a spin- and angle-resolved photoelectron spectroscopy using synchrotron radiation for a thin-film of Fe₄N epitaxially grown on the MgO substrate. We have found electron pockets centered at Γ point as well as M point that are all assigned to be of minority spin. By comparing the experimental result with the first-principles calculation, the electron pockets near Γ and M points are mainly composed of Fe 3d t_2g and e_g orbitals, respectively, which may assist to understand the anomalous conductivities of Fe₄N.

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[2] K. Ito, J. Wang, Y. Shimada, H. Sharma, M. Mizuguchi, and K. Takanashi, J. Appl. Phys. 132, 133904 (2022).