Magnetic features of hybrid transition metal-rare earth nanoparticles: Monte Carlo simulations

Magnetic features of transition metal (TM)-Rare earth (RE) heterostructures were studied using atomistic simulations. The ferromagnetic ordering temperature of pure Cobalt (Co) and Dysprosium (Dy) nanoparticles were reproduced, then hybrid structures of Co and Dy were simulated following the same approach, where the emphasis is mainly laid on the influence of exchange energy which plays a key role in the magnetic ordering of materials. In the framework of Heisenberg spin Hamiltonian, we study the effect of interfacial exchange coupling on the Temperature-dependent magnetization of Co@Dy, Dy@Co, and Co@Dy@Co hybrid nanoparticles using Monte-Carlo (MC) simulations. The hybrid nanostructures created reveal interesting magnetization-temperature features. The effect of the sign of interfacial coupling constant, chemical arrangement, and the thickness of the spacer (Dy in the case of multi-shell Co@Dy@Co) is investigated. The transition of nanoparticles to a paramagnetic state & the associated spin structures display an intriguing pattern. Antiferromagnetic (AFM) coupled nanoparticles (NPs) display a compensation temperature in their M-T plot that is a characteristic of Ferrimagnetic (FI) NPs.