The giant anomalous Hall and Nernst effects in Kagome permanent magnets RCo5

Abstract

Kagome lattice materials have attracted considerable attention due to their intriguing topological properties and potential applications in next-generation quantum and spintronic technologies. In particular, rare-earth permanent magnets with Kagome structure provide an ideal platform that combines robust magnetism with nontrivial quantum phenomena. However, their anomalous transport properties, particularly thermoelectric responses, remain insufficiently explored. In this work, we perform systematic first-principles calculations on the anomalous Hall and anomalous Nernst effects in Kagome permanent magnets RCo5 (R = Ce, La, Sm, Gd). We find that CeCo5 exhibits a pronounced anomalous Hall conductivity of about 1500 Omega^-1 cm^-1 while GdCo5 displays a substantial anomalous Nernst conductivity of 11 A m^-1 K^-1 within +/- 0.1 eV of the Fermi energy, both comparable to or surpassing the measured intrinsic values reported in many typical Weyl and Heusler magnets. These exceptional anomalous transport properties originate from Berry curvature hotspots near spin-orbit coupling induced band gaps. If validated, these theoretical predictions would be important for Berry-curvature-driven transport in magnetic intermetallics. Our results establish RCo5 compounds as versatile platforms for exploring Berry curvature-driven transport in tunable magnetic topological materials.

Figures (8)

• Figure 1: Crystal and electronic structure of $RCo_5$. (a) Crystal structure of $RCo_5$ compounds constructed with the VESTA program [60]. (b) The first Brillouin zone and high-symmetry lines. (c) Spin-summed band structure and density of states of CeCo$_5$, calculated with spin-orbit coupling (SOC). (d)-(i) present the three-dimensional Fermi surfaces of the six bands crossing the Fermi level in CeCo$_5$.
• Figure 2: Calculated anomalous Hall conductivity (AHC) for CeCo$_5$ (a), LaCo$_5$ (b), SmCo$_5$ (c), and GdCo$_5$ (d), respectively. The green lines highlight the maximum AHC values within $\pm 0.1$ eV of the Fermi level for each compound, with the corresponding energy positions and magnitudes indicated by green circles.
• Figure 3: Berry curvature analyses of CeCo$_5$. (a, c) The Berry curvature distributions on the $k_z=0.2$ and $k_z=0.4$ planes of the Brillouin zone, respectively. Panels (b, d) are the corresponding band structures along the $\Gamma$–M–K–$\Gamma$ path colored by the values of the Berry curvature. The positions marked by green ellipses correspond to the Berry curvature hotspots in panels (a) and (c).
• Figure 4: Band structure and symmetry analysis. (a) and (b) are the band structures with $k_z=0.2$ and $k_z=0.4$, respectively. The lower row shows zoomed-in views of the regions enclosed by green ellipses in the upper panel. The lower panel of (b) also shows the irreducible representations of the bands.
• Figure 5: Schematic models illustrating the origin of the Berry curvature from SOC-induced band gaps. (a) Band inversion forms a nodal ring without SOC (left panel), with vanishing Berry curvature across the momentum space (middle panel). Right panel: SOC opens a gap along the ring, generating a ring-like Berry curvature hotspot. (b) Two linear bands cross at a Dirac point. SOC lifts the degeneracy and induces a peaked Berry curvature centered at the gap. These two mechanisms correspond to the scenarios in Fig. \ref{['fig4']}(a)–(b) and account for the Berry curvature distributions shown in Fig. \ref{['fig3']}(a) and Fig. \ref{['fig3']}(c), respectively.