Dipolar interaction effects in the magnetic and magnetotransport properties of ordered nanoparticle arrays

TL;DR

This study uses Monte Carlo simulations to analyze how dipolar interactions influence the magnetic and magnetotransport properties of ordered nanoparticle arrays, revealing anisotropic behaviors and effects of structural parameters.

Contribution

It provides a detailed numerical analysis of dipolar interaction effects on magnetic and transport properties in ordered nanoparticle arrays, including structural and internal nanoparticle influences.

Findings

Dipolar interactions cause anisotropic magnetic behavior in nanoparticle arrays.

Structural parameters like interparticle separation affect magnetic properties.

Simulation results align with experimental measurements on Fe and Co nanoparticle arrays.

Abstract

Assemblies of magnetic nanoparticles exhibit interesting physical properties arising from the competition of intraparticle dynamics and interparticle interactions. In ordered arrays of magnetic nanoparticles magnetostatic interparticle interactions introduce collective dynamics acting competitively to random anisotropy. Basic understanding, characterization and control of dipolar interaction effects in arrays of magnetic nanoparticles is an issue of central importance. To this end, numerical simulation techniques offer an indispensable tool. We report on Monte Carlo studies of the magnetic hysteresis and spin-dependent transport in thin films formed by ordered arrays of magnetic nanoparticles. Emphasis is given to the modifications of the single-particle behavior due to interparticle dipolar interactions as these arise in quantities of experimental interest, such as, the magnetization, the susceptibility and the magnetoresistance. We investigate the role of the structural parameters of an array (interparticle separation, number of stacked monolayers) and the role of the internal structure of the nanoparticles (single phase, core-shell). Dipolar interactions are responsible for anisotropic magnetic behavior between the in-plane and out-of-plane directions of the sample, which is reflected on the investigated magnetic properties (magnetization, transverse susceptibility and magnetoresistance) and the parameters of the array (remanent magnetization, coercive field, and blocking temperature). Our numerical results are compared to existing measurements on self-assembled arrays of Fe-based and Co nanoparticles is made.