Magnetic properties of single atoms and nanostructures on metal surfaces

The developments in the field of nanotechnology made possible studies of
the magnetic properties of the smallest artificially created
nanostructures on metal surfaces: single magnetic atoms and their
clusters. These systems exhibit interesting many-particle effects
(collective magnetic excitations, substrate-mediated magnetic
coupling, Kondo effect) and they may have potential applications in the
field of data storage and data processing.
I will briefly describe one of the main experimental tools in this
field,
the scanning tunneling microscope (STM) and its use for measuring
magnetic
properties at the single-atom level. It is possible to determine the
spin
of an adsorbed atom, its g-factor, the magnetic anisotropy D and E, the
exchange
interaction between pairs of adsorbed atoms, J, and the Kondo
temperature.
I will describe the Kondo impurity model which applies to these systems,
the physics of the local momentum screening, and the role of the
magnetic anisotropy.
I will present the results for the Kondo resonance splitting in the
magnetic field
in the case of an adsorbate with spin S=3/2 and planar magnetic
anisotropy,
obtained using the numerical renormalization group techniques. The
results agree well with recent experimental measurements in the system
of cobalt adsorbed on
a thin copper-nitride layer on the surface of copper.