Helicity-dependent photocurrents in the chiral Weyl semimetal RhSi

Weyl semimetals are crystals in which electron bands cross at isolated points in momentum space. Associated with each crossing point (or Weyl node) is an integer topological invariant known as the Berry monopole charge. The discovery of new classes of Weyl materials is driving the search for novel properties that derive directly from the Berry charge. The circular photogalvanic effect (CPGE), whereby circular polarized light generates a current whose direction depends on the helicity of the absorbed photons, is a striking example of a macroscopic property that emerges from Weyl topology. Recently, it was predicted that the rate of current generation associated with optical transitions near a Weyl node is proportional to its monopole charge. In Weyl semimetals that retain mirror symmetry the current is strongly suppressed by contributions from energy equivalent nodes of opposite charge. However, when all mirror symmetries are broken, as in chiral Weyl systems, nodes with opposite topological charge are no longer degenerate, opening a window of photon energies where the CPGE derived from the topological band structure can emerge. In this work we report the photon-energy dependence of the CPGE in the chiral Weyl semimetal RhSi. The spectrum reveals a helicity-sensitive response in a low-energy window that closes at 0.65 eV, in quantitative agreement with the bandstucture recently predicted from DFT calculations.

Identifier
Source https://archive.materialscloud.org/record/2020.0034/v1
Metadata Access https://archive.materialscloud.org/xml?verb=GetRecord&metadataPrefix=oai_dc&identifier=oai:materialscloud.org:357
Provenance
Creator Rees, Dylan; Manna, Kaustuv; Lu, Baozhu; Morimoto, Takahiro; Borrmann, Horst; Felser, Claudia; Moore, Joel; Torchinsky, Darius; Orenstein, Joseph
Publisher Materials Cloud
Publication Year 2020
Rights info:eu-repo/semantics/openAccess; Creative Commons Attribution 4.0 International https://creativecommons.org/licenses/by/4.0/legalcode
OpenAccess true
Contact archive(at)materialscloud.org
Representation
Language English
Resource Type Dataset
Discipline Materials Science and Engineering