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Abstract

So far, the circular photogalvanic effect (CPGE) is the only possible quantized signal in Weyl semimetals. With inversion and mirror symmetries broken, Weyl and multifold fermions in band structures with opposite chiralities can stay at different energies and generate a net topological charge. Such a kind of net topological charge can present as a quantized signal in the circular polarized light-induced injection current. According to current theoretical understanding, RhSi and its counterparts are believed to be the most promising candidates for the experimental observation of the quantized CPGE. However, a real quantized signal has yet to be experimentally observed. Since previous theoretical studies for the quantized CPGE were based on an effective model but not realistic band structures, it should lose some crucial details that influence the quantized signal. The current status motivates us to perform a realistic ab initio study for the CPGE. Our result shows that RhSi and PtAl in chiral multifold semimetals are alternative materials for obtaining the quantized CPGE which is very easy to be interfered with by trivial band-related optic transitions, and a fine tuning of the chemical potential by doping is essential for the observation of the quantized CPGE. We perform an ab initio analysis for the quantized CPGE based on a realistic electronic band structure and provide an effective way to solve the current problem for the given materials.