Berry curvature enhanced anomalous Hall effect in the ferromagnetic rare-earth compound NdGaSi

Abstract

Rare-earth compounds provide a fertile platform for exploring the interplay between localized 4f  magnetism, spin–orbit coupling (SOC), and emergent electronic topology, often leading to unconventional transport phenomena such as large anomalous Hall effects (AHEs). Among these systems, NdGaSi, a centrosymmetric body-centered tetragonal compound is the subject of interest due to its strong anomalous Hall response. Here, we combine magnetization, electrical transport, specific heat capacity, and single-crystal neutron diffraction measurements with first-principles calculations to elucidate the microscopic origin of this behavior. We show that NdGaSi undergoes a ferromagnetic transition below TC≈11 K, with moments aligned along the crystallographic c  axis. In the ordered state, it exhibits a large anomalous Hall conductivity approaching ∼850 Ω−1cm−1  and a sizable anomalous Hall angle of ∼3%. Electronic structure calculations reveal multiple band crossings and avoided crossings near the Fermi level, resulting in a concentration of Weyl nodes within ∼50  meV below EF, which generate pronounced Berry-curvature hotspots in momentum space. The electronic structure calculated anomalous Hall conductivity reaches ∼840 Ω−1cm−1  below the Fermi level and remains substantial at EF, which aligns with the experimental value. Taken together, our results indicate that the AHE in NdGaSi is predominantly governed by intrinsic Berry-curvature contributions arising from low-energy band structure features shaped by SOC and magnetic order. These findings establish NdGaSi as a compelling example of a rare-earth intermetallic where ferromagnetism and electronic topology act in concert to produce a large transverse response.