The effect of the domain wall (DW) on the conductance in a ballistic ferromagnetic nanowire (FMNW) is revisited by exploiting a specific perturbation theory which is effective for a thin DW; the thinness is often the case in currently interested conductance measurements on FMNW’s. Including the Hund coupling between carrier spins and local spins in a DW, the conductance of a FMNW in the presence of a very thin DW is calculated within the Landauer-Büttiker formalism. It is revealed that the conductance plateaus are modified significantly, and the switching of the quantization unit from $e^2/h$ to about ${2e}^2/h$ is produced in a FMNW by the introduction of a thin DW. This accounts well for recent observations in a FMNW.

• Received 18 October 1999

DOI:https://doi.org/10.1103/PhysRevB.61.11278