Modelling the Influence of Size Distribution and Effective Magnetic Anisotropy Constants on the Magnetic Hyperthermia Process

Abstract

Background: This paper presents a series of theoretical studies about the influence of the size distribution and the effective magnetic anisotropy constants on the Néel relaxation time, the effective relaxation time and the Specific Loss Power of a magnetic nanoparticle system. Methods: We modelled the system by considering the dipolar magnetic interactions among the nanoparticles. Therefore, the Néel relaxation time has been modelled by considering the local magnetic field (i.e., the external magnetic field plus the local magnetic dipolar field) as oblique to each nanoparticle's anisotropy axis. The contribution of our studies have practical applications. In fact, our goal is to propose a robust and reliable model able to optimise the heating process and, consequently, the Specific Loss Power in magnetic hyperthermia applications. Results: In our work, we checked how the dynamic behaviour of monodomain nanoparticles is ifluenced not only by energy barriers but also by a number of other parameters that depend on the effective magnetic anisotropy constants, of the local magnetic field and thus implicitly of the nanoparticle sizes. Conclusion: Our studies contribute to a deeper understanding of the magnetic hyperthermia process and finding ways to control the system parameters for optimising the heating process and, consequently, the Specific Loss Power. Keywords: Hyperthermia process, magnetic modelling, magnetic nanoparticle, specific loss power.