Role of magnetic anisotropy on the heating mechanism of Co-doped Fe3O4 nanoparticles

The heating characteristics of CoxFe3-xO4 (x = 0, 0.1, and 0.3) nanoparticles of average particle size 10–12 nm were investigated. The electron spin resonance analysis revealed an enhancement in magnetic anisotropy from 16 to 21 kJm−3 with low Co doping of x = 0.1. Magnetic measurements performed at 15 K showed a coercivity of 290 kAm−1 for the x = 0.1 composition, that decreased to 37 kAm−1 on surface modification. The effective specific absorption rate (ESAR) obtained using infrared thermography demonstrated a decreasing trend from 3.16 to 2.84 nHm2kg−1 due to the increase in magnetic anisotropy associated with Co substitution. An increase in ESAR up to 4.42 nHm2kg−1 was estimated with surface modification of Co-doped Fe3O4. The theoretically estimated ESAR considering polydispersity and experimental results presented decreasing behavior with magnetic anisotropy as per the linear response theory. •Co-doped Fe3O4 nanoparticles were obtained with an average size of 10-12 nm.•Electron spin resonance experiment indicated magnetic anisotropy of 21 kJm-3 with low Co-doping.•Effective specific absorption rate (ESAR) increases with decreasing magnetic anisotropy.•ESAR value reached a maximum of 4.42 nHm2kg-1 with surface modification.•Particles that comply with linear response theory exhibit better heating efficiency.