We report on a spectroscopic, enantiomer-dependent study of the linear (LPGE) and circular photogalvanic effect (CPGE) in the structurally chiral multifold fermion material PdGa using THz emission. Both bulk and surface responses were measured in right- and left-handed enantiomers over the $0.48–1.1\mathrm{eV}$ incoming photon energy range. The effect of structural handedness was to invert the polarity of the emitted THz transients, yielding spectra roughly equal in magnitude but opposite in sign for all responses measured, with positive (negative) signals generally corresponding to right- (left-) handed samples. All spectra showed evidence of an intraband component and a previously reported interband resonance originating from transitions between the $\mathrm{\Gamma }$ and $\mathrm{R}$ points of the Brillouin zone. The spectra deriving from the helicoidally dispersing surface states closely matched that of the bulk, whereas the direction of the CPGE surface response rotated in opposite directions as a function of driving photon energy for the two enantiomers, revealing their complementary, helicoidally dispersing nature.

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• Chirality
• Nonlinear optics
• Second order nonlinear optical processes
• Topological materials
• Weyl semimetal