(A) Representative TEM image of hexagonal iron oxide nanoparticles doped with Co and Mn (CoMn-IONP). (B) Representative EDX spectrum of CoMn-IONP demonstrating the presence of Co, Mn, and Fe in CoMn-IONPs. (C) Co, Fe, Mn and oxygen (O) EDX line scanning profile of a single CoMn-IONP confirms that Co and Mn are distributed throughout the nanoparticle. (D) Magnetization curves of CoMn-IONP (red) and spherical IONP (black) at room temperature. The magnetization values were normalized by the total weight of nanoparticles. (E) Heating profiles of CoMn-IONP and IONP dispersed in THF (1 mg Fe/mL) and subjected to AMF (420 kHz, 26.9 kA/m).