Using Electronic Coupling To Control Magnetic Properties at the Atomic Scale

by Cyrus F Hirjibehedin (London Centre for Nanotechnology)

Tuesday 1 Apr 2014, 11:00 → 12:00 Europe/Stockholm

Nordita West (122:026)

The drive to continue Moore’s Law by shrinking electrical components down to the ultimate limit has led to a great deal of interest in atomic and molecular-scale electronics, in which individual atoms and molecules can be used as circuit elements. More recent proposals also seek to exploit the magnetic properties of these nanoscale objects in new applications in information technology and spintronics. In typical device geometries, the magnetic element is coupled to electrical leads, and these interactions can strongly affect the properties of the quantum system. Using scanning tunneling microscopy and spectroscopy, we study the effects of interactions between individual magnetic atoms and molecules that are separated from an underlying metallic surface by a thin-insulating layer of copper nitride (Cu2N). For Co atoms on large Cu2N islands, we find that exchange coupling of the spin to the metallic bath can result in Kondo screening as well as dramatically shifting the energy levels of the spin and modifying its effective magnetic anisotropy [1], the property that determines the stability of its spin orientation. By controlling the exchange coupling, we can tune both the Kondo screening of the systems as well as the anisotropy energy over a broad range of values. Furthermore, this system constitutes one of the few cases in which an open quantum system’s energy levels, rather than just its excited-state lifetimes, can be controllably and observably renormalized. [1] J.C. Oberg et al., Nature Nanotechnology 9, 64–68 (2014).