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PGI-1 Talk: Prof. Dr. Fernando Delgado

Exploring the magnetic properties of single atoms on surfaces

30 Oct 2019 11:30
PGI Lecture Hall

Univ. de la Laguna, Tenerife, Spain


Single magnetic atoms on surfaces are the ultimate limit of the magnetic domains used for data storage. Interestingly, they can display spin-excitations, as probed by inelastic electron tunneling spectroscopy (IETS), and long relaxation times, exceeding the microsecond time scale. Their magnetic moments can be manipulated by spin-polarized currents or give place to magnetic resonance response under an applied radiofrequency. Scanning tunneling microscopes (STM) are commonly used to manipulate, probe and engineer these atomic-scale magnets.

Quite often these systems are described by means of phenomenological models, with a clear drawback: they lack of predictive character. While ab-initio density functional theory (DFT) calculations usually provides valuable and accurate structural information, the microscopic description of the magnetic properties of single adatoms still comprises a formidable challenge.

Here I present a detail study of the magnetic properties of Fe adatoms atop N on a Cu2N/Cu(100) surface studied by a combination of DFT calculations and a multiobital Hubbard model derived from the former. This model, in combination with a cotunneling description of the tunneling current, permits analyzing the spin dynamics and it yields the dI/dV spectrum directly observed experimentally by STM. The method not only accounts for the observed spin excitations, but also for the first observation of a pure orbital moment excitation in an adatom.


Prof. Dr. Samir Lounis
Phone: +49 2461 61-4068
Fax: +49 2461 61-2850
email: s.lounis@fz-juelich.de