LandauZener and Rabi oscillations in the spindependent conductance
Abstract
We describe the spindependent quantum conductance in a wire where a magnetic field is spatially modulated. The change in direction and intensity of the magnetic field acts as a perturbation that mixes spin projections. This is exemplified by a ferromagnetic nanowire. There the local field varies smoothly its direction generating a domain wall (DW) as described by the wellknown CabreraFalicov model. Here, we generalize this model to include also a strength modulation. We identify two striking diabatic regimes that appear when such magnetic inhogeneity occurs. 1) If the field strength at the DW is weak enough, the local Zeeman energies result in an avoided crossing. Thus, the spinflip probability follows the LandauZener formula. 2) For strong fields, the spindependent conductance shows oscillations as a function of the DW width. We interpret them in terms of Rabi oscillations. Time and length scales obtained from this simplified view show an excellent agreement with the exact dynamical solution of the spindependent transport. These results remain valid for other situations involving modulated magnetic structures and thus they open new prospects for the use of quantum interferences in spinbased devices.
This paper is dedicated to the memory of the lifelong collaborator Patricia Rebeca Levstein.
 Publication:

EPL (Europhysics Letters)
 Pub Date:
 January 2014
 DOI:
 10.1209/02955075/105/17005
 arXiv:
 arXiv:1305.2887
 Bibcode:
 2014EL....10517005F
 Keywords:

 Condensed Matter  Mesoscale and Nanoscale Physics
 EPrint:
 6 pages, 5 figures