Probing the configurational entropy-magnetic properties connection in a spinel high entropy oxide

Developing structure-properties relationships is a key step in the understanding of new materials, for fundamental and applied research. High entropy oxides (HEOs) — systems where a lattice site is shared by at least five elements — are a class of materials with tantalizing physical and chemical properties. Notably, long range magnetic order emerges in the presence of extreme chemical disorder, making them a great case study for magnetism in the extremely disordered limit. However, the link between configurational entropy and the unique properties of HEOs remains poorly understood. In this work, we explore the entropy-magnetism connection in (Cr,Mn,Fe,Co,Ni)₃O₄, a ferrimagnetic high entropy spinel. To this end, we use x-ray magnetic circular dichroism (XMCD) experiments, resulting in elementally resolved magnetometry where the spin moment of each cation can be tracked over a wide temperature range. We map the magnetically ordered regime analyizing whether the magnetic transition is driven by all cations equally (a true collective property) or if specific cations drive the magnetic transition. Through our study, we gain an improved understanding of the role of configurational entropy in shaping the magnetic properties of HEOs.