EMP is funded through the Horizon2020 programme of the European Commission.
Selected Publications

Giant spontaneous Hall effect in a nonmagnetic Weyl–Kondo semimetal

Sami Dzsaber, Xinlin Yan, Mathieu Taupin, Gaku Eguchi, Andrey Prokofiev, Toni Shiroka, Peter Blaha, Oleg Rubel, Sarah E. Grefe, Hsin-Hua Lai, Qimiao Si, Silke Paschen

Nontrivial topology in condensed-matter systems enriches quantum states of matter to go beyond either the classification into metals and insulators in terms of conventional band theory or that of symmetry-broken phases by Landau’s order parameter framework. So far, focus has been on weakly interacting systems, and little is known about the limit of strong electron correlations. Heavy fermion systems are a highly versatile platform to explore this regime. Here we report the discovery of a giant spontaneous Hall effect in the Kondo semimetal Ce3Bi4Pd3 that is noncentrosymmetric but preserves time-reversal symmetry. We attribute this finding to Weyl nodes—singularities of the Berry curvature—that emerge in the immediate vicinity of the Fermi level due to the Kondo interaction. We stress that this phenomenon is distinct from the previously detected anomalous Hall effect in materials with broken time-reversal symmetry; instead, it manifests an extreme topological response that requires a beyond-perturbation-theory description of the previously proposed nonlinear Hall effect. The large magnitude of the effect in even tiny electric and zero magnetic fields as well as its robust bulk nature may aid the exploitation in topological quantum devices.

Proc Natl Acad Sci USA 118, e2013386118 (2021)

doi: 10.1073/pnas.2013386118