• 26 April 1999
Abstract
The structure and properties of a geometrically constrained magnetic wall in a constriction separating two wider regions are investigated theoretically. It is shown that the structure and the properties of such a wall differ considerably from those of an unconstrained wall, so that the geometrically constrained magnetic wall truly constitutes a new kind of magnetic wall, besides the well known Bloch and Neel walls. In particular, the wall width of a geometrically constrained magnetic wall cann become very small if the characteristic length of the constriction is small, as is actually the case in an atomic point contact. This provides a simple, natural explanation for the large magnetoresistance which has been recently observed in ferromagnetic atomic point contacts.