Spin state of nickel ions and electrical behaviour in entropy-stabilized rare-earth nickelate Ln4Ni3O10

Superconductivity has been realized in rare-earth nickelates, yet only at extreme conditions: either as strained thin films or under high pressure. Owing to the narrow lattice-tolerance window, compositional tuning is severely restricted by conventional synthesis. To circumvent this bottleneck, we have prepared a series of multiple rare-earth Ln4Ni3O10 (Ln = La, Pr, Nd, Sm, and Eu) samples through an entropy stabilization strategy. The increased configurational entropy expands the lattice tolerability of the samples and enhances the tunability of their physical properties. Heat capacity, resistivity and magnetization measurements reveal pronounced changes in electric and magnetic behaviours across the series. The electric response appears may due to the effect of configurational entropy rising. X-ray diffraction and X-ray photoemission spectroscopy indicate that the magnetization variations may stem from spin state change of Ni ions, which triggered by a progressive distortion of Ni-O octahedra. Superconductivity in rare-earth nickelates is typically achieved under extreme conditions, limiting compositional flexibility. Here, the authors employ an entropy stabilization strategy to synthesize Ln4Ni3O10 samples, enhancing lattice tolerability and tunability of physical properties, with significant changes in electric and magnetic behaviors across the lanthanide series.