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Helicity-dependent photocurrents in the chiral Weyl semimetal RhSi.

  • Author(s): Rees, Dylan
  • Manna, Kaustuv
  • Lu, Baozhu
  • Morimoto, Takahiro
  • Borrmann, Horst
  • Felser, Claudia
  • Moore, JE
  • Torchinsky, Darius H
  • Orenstein, J
  • et al.
Abstract

Weyl semimetals are crystals in which electron bands cross at isolated points in momentum space. Associated with each crossing point (or Weyl node) is a topological invariant known as the Berry monopole charge. The circular photogalvanic effect (CPGE), whereby circular polarized light generates a helicity-dependent photocurrent, is a notable example of a macroscopic property that emerges directly from the topology of the Weyl semimetal band structure. Recently, it was predicted that the amplitude of the CPGE associated with optical transitions near a Weyl node is proportional to its monopole charge. In chiral Weyl systems, nodes of opposite charge are nondegenerate, opening a window of wavelengths where the CPGE resulting from uncompensated Berry charge can emerge. Here, we report measurements of CPGE in the chiral Weyl semimetal RhSi, revealing a CPGE response in an energy window that closes at 0.65 eV, in agreement with the predictions of density functional theory.

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