From Chemical Complexity to Tunable Magnetic Ordering in Highly Disordered High-Entropy Spinel Oxides

Neha Sharma; Sushanta Mandal; Nikita Sharma; Amritpal; Sangeeta Thakur; Viktor Ukleev; Chen Luo; Florin Radu; S. D. Kaushik; Tirthankar Chakraborty; Sanjoy Kr. Mahatha; Denis Pelloquin; Sourav Marik

paper

From Chemical Complexity to Tunable Magnetic Ordering in Highly Disordered High-Entropy Spinel Oxides

arXiv:2609.37792

Abstract

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, (Ni $_{0.2}$ Mg $_{0.2}$ Co $_{0.2}$ Cu $_{0.2}$ Zn $_{0.2}$ )B $_{2}$ O $_{4}$ . Upon introducing multicomponent B-site configurations, we uncover a strikingly linear dependence of the magnetic transition temperature (T $_{C}$ ) on the T $_{C}$ s of the corresponding single B-site high-entropy systems. Remarkably, this trend persists even in highly complex (Ni $_{0.2}$ Mg $_{0.2}$ Co $_{0.2}$ Cu $_{0.2}$ Zn $_{0.2}$ )(Cr $_{0.2}$ Mn $_{0.2}$ Fe $_{0.2}$ Ga $_{0.2}$ X $_{0.2}$ ) $_{2}$ O $_{4}$ , X = Al and Ti. Despite the material's extremely high degree of disorder, 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 an emergent 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.