Nanoelectronic device properties are usually influenced rather strongly by impurities and atomistic disorder. Examples are electron scattering by dopants in semiconductor nano-wires, spin scattering by disorder in magnetic tunnel junctions, and spin polarized current in dilute magnetic semiconductors. Theoretically, any calculated transport quantity must be averaged over the ensemble of possibl...

This paper presents a review of the work performed by the authors to incorporate the inner structure of a d-shell magnetic atom in the description of the many-body interaction between a transition metal atom impurity and a metal host. Two main assumptions are made in this approach: (i) the magnetic atom has an orbital singlet with a total electronic spin S (as corresponds to a case for which th...

The chemical selectivity and great sensitivity of the Extended X-ray Absorption Spectroscopy technique allowed the determination, in the paramagnetic phase, of the structural distortions induced by doping in the spin-Peierls CuGeO3 compound. The distorted environments were analyzed as a function of concentration, magnetic nature of impurity and the substitution site (Ni, Mn and Zn impurities on...

We investigate the formation of magnetic Bose polaron, an impurity atom dressed by spin-wave excitations, in a one-dimensional spinor gas. In terms effective potential model is strongly confined host excitations which can even overcome impurity-medium repulsion leading to self-localized quasi-particle state. The phase diagram attractive and self-bound repulsive non-magnetic (Fr{\" o}hlich-type)...

The renormalization group formalism was applied to calculate the spinlattice relaxation rate T 1 of a well-defined magnetic moment in the neighborhood of a spin degenerate Anderson impurity. In the Kondo regime, T 1 in function of the temperature T presents a peak at the Kondo temperature Tk; for T ≪ Tk, the system behaves as a heavy Fermy liquid, with an enhanced density of states, which incre...

We have studied the magnetic excitations in impurity doped La1.85Sr0.15Cu1−yAyO4 (A=Ni or Zn) by neutron scattering. The dispersion for Zn:y = 0.017 is similar to that for the impurity free sample: incommensurate peaks with the incommensurability δ = 0.12 ± 0.01 (rlu) do not change their positions up to 21 meV. On the other hand, for Ni:y = 0.029, two incommensurate peaks observed at low energi...

Using a gradient-corrected density functional method, we studied computationally how single impurity atoms affect the structure and the properties of a Ni4 cluster. H and O atoms coordinate at a Ni-Ni bond, inducing small changes to the structure of bare Ni4 which is essentially a tetrahedron. For a C impurity, we found three stable structures at a Ni4 cluster. In the most stable geometry, the ...