From Chemical Complexity to Magnetic Tunability in High-Entropy Spinel Oxides

High-entropy stabilization chemistry is redefining materials design by transforming configurational disorder, arising from the deliberate incorporation of multiple principal cations, into a thermodynamic advantage that promotes phase stability and enables emergent functionalities. In this work, we investigate the evolution of magnetic ordering in spinel-type high-entropy oxides by systematically varying the cation composition of the B site within a fixed high-entropy A-site matrix (nominal composition), (Ni0.2Mg0.2Co0.2Cu0.2Zn0.2)B2O4. Upon introducing multicomponent B-site configurations, we uncover a strikingly linear dependence of the magnetic transition temperature (TC) on the TCs of the corresponding single-B-site high-entropy systems. Remarkably, this trend persists even in highly complex (Ni0.2Mg0.2Co0.2Cu0.2Zn0.2)(Cr0.2Mn0.2Fe0.2Ga0.2X0.2)2O4, X = Al and Ti. Despite the material’s extremely high degree of disorder and the absence of a dominant magnetic ion or a straightforward superexchange pathway, detailed magnetization measurements, low-temperature X-ray magnetic circular dichroism, and neutron powder diffraction studies reveal robust long-range ferrimagnetic ordering. These results reveal a predictability in ferrimagnetic high-entropy spinel oxides, where, despite extreme configurational disorder and competing interactions, robust ferrimagnetic order can arise from, rather than be hindered by, extreme configurational disorder. This establishes a pathway for predictively tuning magnetic transition temperatures in high-entropy oxides beyond conventional ordered systems.