Weyl-Kondo semimetals: Symmetries, signatures and nearby quantum phases*

In the last few years, manifestations of the long-anticipated Weyl semimetal have been observed in weakly correlated materials. In the context of a global phase diagram for strongly correlated systems with a large spin-orbit coupling, the prototypical heavy fermion systems have emerged as an important platform for topological metals. We have recently advanced a strongly correlated topological phase, the Weyl-Kondo semimetal (WKSM) [1], which exhibits Kondo effect-driven nodal quasiparticles. The Weyl nodes are pinned near the Fermi energy by strong correlations along with space group symmetry. One signature of this WKSM phase is a specific heat varying as T³ below the Kondo temperature, with a colossal prefactor, as observed in the noncentrosymmetric heavy fermion semimetal Ce₃Bi₄Pd₃ [2]. Experiments on Ce₃Bi₄Pd₃ have also demonstrated a nonlinear spontaneous Hall response and an even-in-field Hall resistivity, which are attributed to the large Berry curvature dipole of a WKSM with tilted nodes [3]. Both illustrate that signatures of topological phases driven by strong correlations are often distinct from those typical for weakly correlated systems. Finally, in related models we have found how the WKSM connects with proximate topologically distinct phases, such as a Kondo Insulator and a Dirac-Kondo semimetal, as well as magnetic states. I will present these results, and discuss their place in the heavy fermion global phase diagram that the topological paradigm has enriched.

[1] H.-H. Lai, S.E. Grefe, S. Paschen and Q. Si, Proc. Natl. Acad. Sci. U.S.A, 115, 93-97 (2018).
[2] S. Dzsaber L. Prochaska, A. Sidorenko, G. Eguchi, R. Svagera, M. Waas, A. Prokofiev, Q. Si and S. Paschen, Phys. Rev. Lett. 118, 246601 (2017).
[3] S. Dzsaber, X. Yan, G. Eguchi, A. Prokofiev, T. Shiroka, P. Blaha, O. Rubel, S. E. Grefe, H.-H. Lai, Q. Si, S. Paschen, arXiv:1811.02819 (2018).