  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.
