Dresden 2009 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 37: Transport: Nanoelectronics II - Spintronics and Magnetotransport
TT 37.2: Vortrag
Donnerstag, 26. März 2009, 09:45–10:00, HSZ 105
Spin-Polarized Conductance in a Single Magnetic Atom? — •Cormac Toher and Gianaurelio Cuniberti — Institute for Materials Science and Max Bergmann Center of Biomaterials, Dresden University of Technology, D-01062 Dresden, Germany.
Single atom conductance measurements can be performed by forming nanocontacts using a scanning tunnelling microscope (STM). In the case of fully spin-polarized transport, a spin resolved conductance quantum of 0.5G0 = e2/h is expected, in contrast to the value of G0= 2 e2/h expected in normal atomic nanocontacts with one full spin degenerate open channel. A spin-resolved conductance has been observed in the experiments carried out by Néel et. al. [1] on cobalt atoms. When the cobalt atom is placed on a copper surface and contacted by a tungsten tip, a conductance of G0 is observed, whereas when it is placed on a cobalt island and contacted by a nickel tip, a conductance of 0.5G0 is observed. Here we present the results of calculations to explore the mechanism underlying this effect, investigating whether or not spin-polarized transport is actually present. These calculations were performed using the ab initio transport method SMEAGOL [2], which combines the non-equilibrium Green function formalism with the DFT implementation SIESTA [3].
[1] N. Néel, J. Kröger, and R. Berndt, Phys. Rev. Lett. (submitted).
[2] A. R. Rocha et. al., Phys. Rev. B 73, 085414 (2006).
[3] J. M. Soler et. al., J. Phys. Cond. Matter 14, 2745 (2002).