Magnetic scanning tunneling microscopy with a two-terminal nonmagnetic tip: Quantitative results - art. no. 165424

We report numerical simulation results of a recently proposed [P. Bruno, Ph ys. Rev. Lett 79, 4593 (1997)] approach to perform magnetic scanning tunnel ing microscopy with a two terminal nonmagnetic tip. It is based upon the sp in asymmetry effect of the tunneling current between a ferromagnetic surfac e and a two-terminal nonmagnetic tip. The spin asymmetry effect is due to t he spin-orbit scattering in the tip. The effect can be viewed as a Mott sca ttering of tunneling electrons within the tip. To obtain quantitative resul ts we perform numerical simulations within the single-band tight-binding mo del, using the recursive Green's-function method and the Landauer-Buttiker formula for conductance. A model has been developed to take into account th e spin-orbit scattering off the impurities within the single-band tight-bin ding model. We show that the spin-asymmetry effect is most prominent when t he device is in the quasiballistic regime and the typical value of spin asy mmetry is about 5%.