A Heavy Fermion Zn-Deficient CaBe2Ge2-Type Phase with Rare Ce-Based Ferromagnetism and Large Magnetoresistance

We report on the hitherto unknown compound CeZn_2−δGe₂ (δ ≈ 0.41). We find that this compound crystallizes in a defect version of the well-known CaBe₂Ge₂ structure type. The phase forms in a Zn/In flux and with Zn deficiency on one of its crystallographic sites. We find that the compound displays uncommon localized Ce-based (4f¹) ferromagnetism with a T_c of 6.6 K, a large positive magnetoresistance reaching an MR of approximately 32% below 10 K, and strongly correlated electrons, as evidenced by a Kadowaki–Woods ratio A/γ² close to those of known heavy fermion compounds. The here discovered material is therefore a promising model platform for the investigation of these entangled interacting and potentially competing electronic states paired with complex crystal chemistry.