X-ray analysis of Mg 0.2 Co 0.2 Ni 0.2 Cu 0.2 Zn 0.2 O: disentangling elemental contributions in a prototypical high-entropy oxide

We employ several X-ray based techniques, including X-ray diffraction, X-ray absorption spectroscopy andresonant inelastic X-ray scattering, to disentangle the contributions of individual chemical species to thestructural, electronic and magnetic properties of high-entropy oxides. In the benchmark compoundMg0.2Co0.2Ni0.2Cu0.2Zn0.2O and related systems, we unambiguously resolve a sizable Jahn–Tellerdistortion at the Cu sites, more pronounced in the absence of Ni2+ and Mg2+, suggesting that these ionspromote positional order, whereas Cu2+ ions act to destabilize it. Moreover, we detect magneticexcitations and estimate the strength of the interactions between pairs of different magnetic elements.Our results provide valuable insights into the role of various chemical species in shaping the physicalproperties of high-entropy oxides