Weyl-Kondo semimetals: From symmetry-based design to non-Fermi liquid topology*

The interplay between interactions and topology in quantum materials is of extensive current interest. For metallic systems, whether and how electron correlations lead to topological states is an open and pressing problem. The notion of Weyl-Kondo semimetal, introduced theoretically [1] and experimentally [2] concurrently, set the stage for progress. We have introduced a general framework, in which gapless topological states are driven by symmetry constraints on correlation-induced emergent excitations [3]. Along this direction, we have i) put forward a design principle to determine new Weyl-Kondo semimetal phases and identify new correlated materials for their realization [4]; and ii) advanced the framework even when the Fermi-liquid description breaks down, and put forward a non-Fermi liquid topological semimetal phase [3] and a new topological semimetal quantum critical point  [5]. Here, the multi-channel Kondo effect or critical fluctuations of the local moments lead to both features of non-Fermi liquid and characteristics of the nontrivial electronic topology [3,5]. Our work opens a new route to studying gapless topological phases in a broad range of strongly correlated materials.

[1] H.-H. Lai et al., “Weyl-Kondo Semimetal in Heavy Fermion Systems'', PNAS 115, 93 (2018).

[2] S. Dzsaber et al., “Kondo Insulator to Semimetal Transformation Tuned by Spin-Orbit Coupling'', Phys. Rev. Lett. 118, 246601 (2017).

[3] Haoyu Hu et al., “Topological semimetals without quasiparticles”, arXiv:2110.06182.

[4] L. Chen et al., “Topological semimetal driven by strong correlations and crystalline symmetry”, Nat. Phys. (published online Sept 2022), https://www.nature.com/articles/s41567-022-01743-4 .

[5] L. Chen, Haoyu Hu, et al., unpublished (2022).