Magnetocaloric Effect and Universal Curve Behavior in Superparamagnetic Zinc Ferrite Nanoparticles Synthesized via Microwave Assisted Co-Precipitation Method

Single domain superparamagnetic zinc ferrite nanoparticles are synthesized through microwave assisted co-precipitation method. Single phase and cubic spinel zinc ferrite nanoparticles shows the narrow particle size distribution with an average particle size of 5.07nm. They exhibits superparamagnetic nature at 290K and ferromagnetism at 5K with a blocking temperature of around 25K. The magnetic entropy change calculated from the set of isothermal magnetization curves shows the maximum entropy change of -0.652Jkg(-1)K(-1) at 135K and large relative cooling power (RCP) of 187Jkg(-1) for the field of 40kOe. The synthesized zinc ferrite nanoparticles exhibits large magnetic anisotropy constant of 12.625x10(6)ergcm(-3) with an appreciable magnetic entropy change. The field dependence of maximum magnetic entropy change and RCP values is discussed by using power law equations. Furthermore, an attempt is made to study the phenomenological curve behavior of magnetic entropy change for the zinc ferrite nanoparticles. Interestingly, the magnetic entropy change at the range of magnetic fields collapses into a single universal phenomenological curve when rescaling the temperature axis with two reference temperatures. The obtained results conveys that the zinc ferrite nanoparticles is prospective magnetic refrigerant for miniaturized devices.