Tuning anomalous Hall conductivity via antiferromagnetic configurations in GdPtBi†

The magnetic, electronic, and topological properties of GdPtBi were systematically investigated using first-principles density functional theory (DFT) calculations. Various magnetic configurations were examined, including ferromagnetic (FM) and antiferromagnetic (AFM) states, with particular focus on AFM states where the Gd magnetic moments align either parallel (AFM_‖) or perpendicular (AFM_⊥) to the [111] crystal direction. For AFM_⊥, the in-plane angles ϕ were varied at ϕ = 0°, 15°, and 30° (denoted as AFM_⊥,ϕ=0°, AFM_⊥,ϕ=15°, and AFM_⊥,ϕ=30°, respectively). The ground-state magnetic structure of GdPtBi was validated through dipolar magnetic field calculations at the muon sites, corroborating the internal magnetic fields observed in muon spin relaxation (μSR) experiments. The results indicate that the AFM_⊥,ϕ=30° configuration aligns with the μSR-measured internal field. The DFT-calculated band structure and Berry curvature reveal that AFM_⊥ belongs to the triple-point semimetals (TPSMs) where the triple-point nodes positioned along the Z–Γ–Z and F–Γ–F paths have energies that shift as the spin–orbit coupling strength varies with ϕ. Notably, this shift in triple-point energy corresponds to a significant change in the anomalous Hall conductivity (AHC, σ_xy), with a difference of 75.06 Ω⁻¹ cm⁻¹ at the Fermi energy between AFM_⊥,ϕ=0° and AFM_⊥,ϕ=30°. These findings highlight the potential for controlling the AHC through precise manipulation of the AFM structure.