Extreme compositional complexity in crystalline perovskite oxide: a new paradigm in quantum materials research

Perovskite oxides ([Formula: see text]O[Formula: see text]) have long been central to the advancement of modern condensed matter physics, owing to their rich and tunable electronic and magnetic properties. The quest to understand their various entangled phases has spurred the development of both cutting-edge experimental tools and innovative theoretical frameworks. In recent times, the emergence of high entropy oxides - materials in which five or more elements share a single crystallographic site - has introduced a powerful new paradigm in materials design. Embedding such extreme chemical disorder within the perovskite framework has opened vast opportunities for realizing novel physical phenomena inaccessible in conventional oxides. This review surveys the rapid advances in the synthesis, characterisation, and exploration of the electronic and magnetic properties of compositionally complex perovskite oxides, offering key insights and highlighting promising avenues for future research.