
**_Physics of a few magnetic atoms adsorbed on a surface_** ** _ ___**
**__F. Delgado 1__** ** _,2_** ** _and J. Fernández-Rossier 3_** __
_1_ _Material Physics Center,_ Manuel de Lardizabal 5 _, Guipúzcoa_ E-20018
(SPAIN) __
_2_ IKERBASQUE, Basque Foundation for Science, Bilbao, 48013, Spain.
3 International Iberian Nanotechnology Laboratory, _Avn.Mestre José Veiga,
4715-330 Braga, Portugal_
Single magnetic atoms adsorbed on surfaces are likely the ultimate limit of
magnetic storage and processing devices [1], and they serve as controllable
systems where the quantum character of magnets emerges. These characteristics
have foster both, the experimental and theoretical study, going from the role
of the magnetic anisotropy, the dissipative dynamics associated with the
coupling to the substrate or the formation of a many body singlet state, the
so called Kondo effect. From the experimental point of view, the Scanning
Tunneling Microscope (STM) makes it possible to fabricate and probe magnetic
nanostructures with atomic resolution, going from individual atoms up to
arrays of spin chains [2].
The theoretical description of these magnetic adsorbates requires to deal with
both, the quantum nature and the dissipative coupling to the environment.
While the first can be accounted for by an effective spin Hamiltonian [2-3],
the energy and momentum transfer can be described by an exchange coupling with
the adsorbate spins [3]. A perturbative treatment of the coupling has
successfully explained the experimentally measured spectral features [2,4,5],
the magnetoresistive response or the spatial variations of the spin waves [6].
**References**
[1] R. Wiesendanger, Rev. Mod. Phys. 81, 1495 (2009)
[2] S. Loth, S. Baumann, C. P. Lutz _et al.,_ Sience **335** , 196 (2012)
[3] F. Delgado and J. Fernández-Rossier, Phys. Rev. B **82** , 134414 (2010)
[4] J. C. Oberg, M. R. Calvo, F. Delgado _et al_., Nature Nanotechnology 9, **64** (2014).
[5] A. Spinelly, B. Bryant, F. Delgado et al., Nature Materials 13, 782 (2014)