Bottom-up strategies for the assembling of magnetic systems using nanoclusters

TL;DR

This paper reviews recent advances in assembling magnetic nanoclusters, focusing on their structural and magnetic properties, and highlights how size and composition influence magnetic behavior in nanostructured systems.

Contribution

It provides new insights into the magnetic properties of nanocluster assemblies, emphasizing interface effects, size-related phenomena, and nanoalloy behaviors using advanced characterization techniques.

Findings

Size reduction enhances magnetic moments.

Interface anisotropy varies with matrix and cluster composition.

Nanoalloy relaxation impacts magnetic anisotropy.

Abstract

In the frame of the 20th Anniversary of the Journal of Nanoparticle Research (JNR), our aim is to start from the historical context twenty, years ago and to give some recent results and perspectives concerning nanomagnets prepared from clusters preformed in the gas phase using the Low Energy Cluster Beam Deposition (LECBD) technique. In this paper, we focus our attention on the typical case of Co clusters embedded in various matrices to study interface magnetic anisotropy and magnetic interactions as a function of volume concentrations, and on still current and perspectives through two examples of binary metallic 3d-5d TM (namely CoPt and FeAu) clusters assemblies to illustrate size-related and nanoalloy phenomena on magnetic properties in well-defined mass-selected clusters. The structural and magnetic properties of these cluster assemblies were investigated using various experimental techniques that include High Resolution Transmission Electron Microscopy (HRTEM), Superconducting Quantum Interference Device (SQUID) magnetometry, as well as synchrotron techniques such as Extended X-Ray Absorption Fine Structure (EXAFS) and X-Ray Magnetic Circular Dichroism (XMCD). Depending on the chemical nature of both NPs and matrix, we observe different magnetic responses compared to their bulk counterparts. In particular, we show how finite size effects (size reduction) enhance their magnetic moment and how specific relaxation in nanoalloys can impact their magnetic anisotropy.