Dimensionality effects in the LDOS of ferromagnetic hosts probed via   STM: spin-polarized quantum beats and spin filtering
  We theoretically investigate the local density of states (LDOS) probed by a STM tip of ferromagnetic metals hosting a single adatom and a subsurface impurity. We model the system via the two-impurity Anderson Hamiltonian. By using the equation of motion with the relevant Green functions, we derive analytical expressions for the LDOS of two host types: a surface and a quantum wire. The LDOS reveals Friedel-like oscillations and Fano interference as a function of the STM tip position. These oscillations strongly depend on the host dimension. Interestingly, we find that the spin-dependent Fermi wave numbers of the hosts give rise to spin-polarized quantum beats in the LDOS. While the LDOS for the metallic surface shows a damped beating pattern, it exhibits an opposite behavior in the quantum wire. Due to this absence of damping, the wire operates as a spatially resolved spin filter with a high efficiency. 
A. C. Seridonio, S. C. Leandro, L. H. Guessi, E. C. Siqueira, F. M.   Souza, E. Vernek, M. S. Figueira and J. C. Egues
cond-mat.str-el cond-mat.mtrl-sci