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

Abstract

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 nHm(2)kg(-1) due to the increase in magnetic anisotropy associated with Co substitution. An increase in ESAR up to 4.42 nHm(2)kg(-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.