Saraswati, A.; Sau, J.; Misheneva, V.; Lou, R.; Chatterjee, S.; Kuila, S.K.; Ghanta, B.; Bera, A.K.; Jana, P.P.; Fedorov, A.; Thirupathaiah, S.; Kumar, M.; Kumar, N.: Accessing quasiflat f bands to harvest large Berry curvature in NdGaSi. Physical Review Materials 10 (2026), p. L031202/1-8
10.1103/djlm-1y1h
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Abstract:
In typical rare-earth lanthanide compounds, the localized 4𝑓 electrons have a weak effect on the electrical conduction, limiting their influence on the Berry curvature and, hence, the intrinsic anomalous Hall effect. A comprehensive study of the magnetic, thermodynamic, and transport properties of single-crystalline NdGaSi, guided by first‐principles calculations, reveals a ferromagnetic ground state that induces a splitting of quasiflat 4𝑓 electronic bands and positions them near the Fermi energy. The observation of an extraordinarily large intrinsic anomalous Hall conductivity of 1165Ω−1cm−1 implies the direct involvement of localized states in the generation of nontrivial band crossings around the Fermi energy. The angle-resolved photoemission spectroscopy measurements provide direct evidence of nontrivial crossing of the 4𝑓 bands with dispersive bands. These results are remarkable when compared to ferrimagnetic NdAlSi, which differs only in a nonmagnetic atom (a change in the principal quantum number 𝑛 of the outer 𝑝 orbital) with the same number of valence electrons and does not exhibit any measurable anomalous Hall conductivity.