High entropy oxides: An emerging prospect for magnetic rare earth - transition metal perovskites

It has been shown that oxide ceramics containing multiple transition and/or rare-earth elements in equimolar ratios have a strong tendency to crystallize in simple single phase structures, stabilized by the high configurational entropy. In analogy to the metallic alloy systems, these oxides are denoted high entropy oxides (HEOs). The HEO concept allows to access hitherto uncharted areas in the multi-element phase diagram. Among the already realized structures there is the highly complex class of rare earth - transition element perovskites. This fascinating class of materials generated by applying the innovative concept of high entropy stabilization provides a new and manyfold research space with promise of discoveries of unprecedented properties and phenomena. The present study provides a first investigation of the magnetic properties of selected compounds of this novel class of materials. Comprehensive studies by DC and AC magnetometry are combined with element specific spectroscopy in order to understand the interplay between magnetic exchange and the high degree of chemical disorder in the systems. We observe a predominant antiferromagnetic behavior in the single phase materials, combined with a small ferromagnetic contribution possibly stemming from small ferromagnetic clusters or configurations in the antiferromagnetic matrix. In the long term perspective it is proposed to screen the properties of this family of compounds with high throughput methods, including combined experimental and theoretical approaches.