Superconductivity, Kondo physics, and magnetic order: Tuning the ground state in the La1−xCexFeSiH solid solution through the interplay between 3d and 4f correlated electrons

Abstract

We report a study of the La1−xCexFeSiH solid solution (0≤x≤1), a family of intermetallic hydrides of ZrCuSiAs-type structure, with space group P4/nmm. For low cerium concentrations x≤0.20, we observe the presence of superconductivity, which originates from the correlated 3d electrons of iron. The superconducting regime is progressively suppressed by the cerium substitution. For moderate cerium concentration 0.07≤x≤0.50, we observe evidence of the single-ion Kondo effect and no magnetic phase transition down to 2 K. For 0.07≤x≤0.20, the single-ion Kondo effect coexists with a superconducting ground state at low temperatures. From x>0.50, we observe signatures of Kondo coherence and a heavy Fermi liquid regime at low temperature. Finally, at high cerium concentration x≥0.85, we observe signatures of magnetic ordering at low temperatures. We discuss our results by introducing temperature scales related to superconductivity, the Kondo effect, and magnetic order, which permits building a rich phase diagram temperature versus cerium content x. This shows that using the cerium concentration x as a unique control parameter, we can explore the Kondo entanglement between correlated 3d and 4f electrons, which suggests an unusual change between the superconducting state related to the 3d electrons and the Kondo coherent state involving both 3d and 4f electrons.

Source-reported materials — not catalogue approval

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