Tuning the van Hove singularities in monolayer PbBiI via C3v symmetry breaking

Various filling fractions of the van Hove singularities (vHs) in the vicinity of the Fermi energy give rise to exotic phenomena. Here, we tune vHs in a new family member of quantum spin Hall insulators PbBiI via two mechanisms of C3v symmetry breaking; applying an in-plane magnetization exchange field and an inversion symmetry breaking field. Depending on the mechanism and dispersion direction of host electrons, we find Weyl nodes in the electronic band structure, and in turn, bare vHs deform away from the Fermi energy. Moreover, the number of vHs increases due to the reconstruction of the Fermi surface induced by the above mechanisms. Overall, we indeed propose two efficient mechanisms to tune/create vHs for various emergent applications in optoelectronics.(c) 2023 Elsevier B.V. All rights reserved.

Automated summary

By tuning the filling fractions of van Hove singularities in PbBiI quantum spin Hall insulators through two mechanisms of C3v symmetry breaking – applying an in-plane magnetization exchange field and an inversion symmetry breaking field – we can induce exotic phenomena, including the formation of Weyl nodes in the electronic band structure and the deformation of bare van Hove singularities away from the Fermi energy. The above mechanisms also lead to the increase in the number of van Hove singularities due to the reconstruction of the Fermi surface. These findings propose two efficient mechanisms for tuning/creating van Hove singularities with potential applications in optoelectronics.