Magnetic nanoparticles with inhomogeneous and core/shell structures

Abstract

In this work, we present the results of atomistic-level simulations of the magnetic properties of individual magnetic nanoparticles (NP) with a variety of morphologies and compo-sitions. For this purpose, we have set up a computer code that uses the Monte Carlo method to simulate Heisenberg classical spins residing on the nodes of different kinds of 3D lattices, includ-ing exchange interactions between them, magnetocrystalline uniaxial anisotropy, and the effect of an external magnetic field. Finite-size and surface effects on the equilibrium magnetic configu-rations and hysteresis loops of single-phase NP have been studied varying the shape and surface anisotropy of the NP. We also present results of the reversal mechanisms of NP with (ferromag-netic (FM)/antiferromagnetic(AF)) core/shell morphology, showing that they exhibit the exchange bias (EB) phenomenon in the hysteresis loops after a field cooling (FC) process and unveiling the microscopic origin of this phenomenon. Finally, the possibility of observing EB effects in NP with inverted core(AF)/shell(FM) structure will be explored and their magnetic properties compared to those with the conventional morphology