X-ray analysis of Mg0.2Co0.2Ni0.2Cu0.2Zn0.2O: disentangling elemental contributions in a prototypical high-entropy oxide

Abstract

We employ several X-ray based techniques, including X-ray diffraction, X-ray absorption spectroscopy and resonant inelastic X-ray scattering, to disentangle the contributions of individual chemical species to the structural, electronic and magnetic properties of high-entropy oxides. In the benchmark compound Mg_0.2Co_0.2Ni_0.2Cu_0.2Zn_0.2O and related systems, we unambiguously resolve a sizable Jahn–Teller distortion at the Cu sites, more pronounced in the absence of Ni²⁺ and Mg²⁺, suggesting that these ions promote positional order, whereas Cu²⁺ ions act to destabilize it. Moreover, we detect magnetic excitations 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 physical properties of high-entropy oxides.