Topological Hopf and Chain Link Semimetal States and Their Application to Co2MnGa

Guoqing Chang, Su Yang Xu, Xiaoting Zhou, Shin Ming Huang, Bahadur Singh, Baokai Wang, Ilya Belopolski, Jiaxin Yin, Songtian Zhang, Arun Bansil, Hsin Lin, M. Zahid Hasan

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Abstract

Topological semimetals can be classified by the connectivity and dimensionality of the band crossings in momentum space. The band crossings of a Dirac, Weyl, or an unconventional fermion semimetal are zero-dimensional (0D) points, whereas the band crossings of a nodal-line semimetal are one-dimensional (1D) closed loops. Here we propose that the presence of perpendicular crystalline mirror planes can protect three-dimensional (3D) band crossings characterized by nontrivial links such as a Hopf link or a coupled chain, giving rise to a variety of new types of topological semimetals. We show that the nontrivial winding number protects topological surface states distinct from those in previously known topological semimetals with a vanishing spin-orbit interaction. We also show that these nontrivial links can be engineered by tuning the mirror eigenvalues associated with the perpendicular mirror planes. Using first-principles band structure calculations, we predict the ferromagnetic full Heusler compound Co2MnGa as a candidate. Both Hopf link and chainlike bulk band crossings and unconventional topological surface states are identified.

Original languageEnglish (US)
Article number156401
JournalPhysical review letters
Volume119
Issue number15
DOIs
StatePublished - Oct 13 2017

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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    Chang, G., Xu, S. Y., Zhou, X., Huang, S. M., Singh, B., Wang, B., Belopolski, I., Yin, J., Zhang, S., Bansil, A., Lin, H., & Hasan, M. Z. (2017). Topological Hopf and Chain Link Semimetal States and Their Application to Co2MnGa. Physical review letters, 119(15), [156401]. https://doi.org/10.1103/PhysRevLett.119.156401