Demonstration of the spin-valve effect in a single-atom contact. The junction is comprised of a Cr-coated scanning tunneling microscope tip and a single Co atom adsorbed on a ferromagnetic Fe film. Left: Experimentally observed conductance evolution of the junction for parallel (green) and antiparallel (red) orientation of the magnetic moments of the tip apex atom and the Co adatom. Dashed lines are exponential fits to the data in the tunnelling and contact regions. Their intersection defines the contact conductance, G_c. Center: sketches of the corresponding single-atom junctions. An antiferromagnetic Cr-covered W tip (yellow) is used to contact a Co atom (blue) adsorbed to a Fe bilayer island (gray). Arrows indicate the magnetic moments of individual atoms. In the top (bottom) panel the magnetic moments of the tip apex atom and the Co atom are parallel (antiparallel). The adatom magnetic moment is reversed by its ferromagnetic coupling to the Fe islands, which exhibit an out-of-plane magnetization. Right: Cross-sectional plots of the local density of states integrated between the Fermi energy and 50 meV above it for a Cr-tip-Co-Fe-W(110) junction based on first-principles calculations. The larger overlap of orbital states in the majority channel of the parallel configuration corresponds to the larger measured conductance values in the parallel configuration between the Cr tip and the Co adatom (left).

For more details refer to the following link:

Full article: New Journal of Physics 13, 085011 (2011)

<<< Back to gallery