Open Access

Diana M. Kirschbaum, Xinlin Yan, Monika Waas, Robert Svagera, Andrey Prokofiev, Berthold Stöger, Gerald Giester, Peter Rogl, Diana-Gabriela Oprea, Claudia Felser, Roser Valentí, Maia G. Vergniory, Jeroen Custers, Silke Paschen, Diego Andres Zocco

• he family of cubic noncentrosymmetric 3-4-3 compounds has become a fertile ground for the discovery of novel correlated metallic and insulating phases. Here, we report the synthesis of a new heavy fermion compound, Ce3⁢Bi4⁢Ni3. It is an isoelectronic analog of the prototypical Kondo insulator Ce3⁢Bi4⁢Pt3 and of the recently discovered Weyl-Kondo semimetal Ce3⁢Bi4⁢Pd3. In contrast to the volume-preserving Pt-Pd substitution, structural and chemical analyses reveal a positive chemical pressure effect in Ce3⁢Bi4⁢Ni3 relative to its heavier counterparts. Based on the results of electrical resistivity, Hall effect, magnetic susceptibility, and specific heat measurements, we identify an energy gap of 65–70 meV, about eight times larger than that in Ce3⁢Bi4⁢Pt3 and about 45 times larger than that of the Kondo-insulating background hosting the Weyl nodes in Ce3⁢Bi4⁢Pd3. We show that this gap as well as other physical properties do not evolve monotonically with increasing atomic number, i.e., in the sequence Ce3⁢Bi4⁢Ni3−Ce3⁢Bi4⁢Pd3−Ce3⁢Bi4⁢Pt3, but instead with increasing partial electronic density of states of the 𝑑 orbitals at the Fermi energy. This work opens the possibility to investigate the conditions under which topological states develop in this series of strongly correlated 3-4-3 materials.