From Diamagnetism to Weak Ferromagnetism: Magnetic Evolution in FeCr Codoped ZnO Nanoparticles

The magnetic properties of transition metal‐doped semiconductors are of significant interest due to their tunability and cost‐effectiveness for spintronic applications. Herein, zinc oxide (ZnO) nanoparticles codoped with iron (Fe) and chromium (Cr) are synthesized via a coprecipitation method with varying dopant concentrations. Structural, morphological, and magnetic properties are systematically investigated. A clear evolution of magnetic behavior is observed with increasing dopant levels: pure ZnO exhibits diamagnetic behavior, Fe‐doped ZnO transitions to a linear M‐H response, and further codoping with Cr induces a weak ferromagnetic response. Notably, the composition Zn 0.90 Fe 0.04 Cr 0.06 O demonstrates optimal magnetic enhancement, marked by a distinct weak ferromagnetic M‐H loop at room temperature. This progression from diamagnetism to weak ferromagnetism highlights the critical role of dopant concentration and the interplay between Fe and Cr ions. The observed ferromagnetic behavior is attributed to Fe/Cr cations substituting Zn sites and exchange interactions mediated by conduction electrons. These findings underscore the potential of FeCr codoped ZnO nanoparticles as promising candidates for room‐temperature spintronic applications.