Charge dynamics of a noncentrosymmetric magnetic Weyl semimetal

The prediction from first-principles calculations that the Weyl fermions in PrAlGe are in proximity of the Fermi level and its established large anomalous Hall conductivity (AHC) below T_C have a significant implication: the enhanced Berry curvature fields associated with those Weyl nodes and concomitant with the broken time-reversal symmetry may deem necessary to generate a large, intrinsic (topological) anomalous Hall effect. PrAlGe is thus an ideal playground in order to chase the elusive ingredients framing the relationship between topology and peculiar transport properties.

By exploring the temperature (T) dependence of the real part (σ₁(ω)) of the optical conductivity (Fig. 1.22), achieved over an extremely broad spectral range, we ultimately capture the spectroscopic hallmark of the intrinsic anomalous Hall effect in PrAlGe.

PrAlGe harbours indeed electronic correlations, which are reflected in a sizeable reduction of the Fermi velocity with respect to the bare band value at low T. At T < T_C, the optical response registers a band reconstruction, which additionally causes a reshuffling of spectral weight (SW), pertinent to the electronic environment of the type-I Weyl fermions and tracing the remarkable AHC (Fig. 1.23). With the support of dedicated first-principles calculations, we provide evidence for the intimate relationship between a topological resonance of the absorption spectrum and the progressively enhanced occupation of non-trivial states with large Berry curvatures. It is worth noting that the intimate relationship between σ_xy^A and the SW reshuffling, pertinent to the excitations around the Weyl nodes and imprinting the Berry curvature, evidences a strong similarity with our previous findings in the van der Waals Fe₃GeTe₂ ferromagnet. We conjecture that this seems to be a generic, common feature in materials displaying large AHC, even benefiting from electronic correlations at low T.