Domain wall scattering explains 300 % ballistic magnetoconductance of nanocontacts

We present theory and experiments in good agreement for ballistic magnetore sistance in nanoscopic-size contacts in 3d metals (Ni and Co). It is found that values of the ballistic magnetoconductance of similar to 300% at room temperature can be explained by scattering by the domain wall which is trap ped in the constriction region. These values are obtained for very small co ntacts and they decrease very fast as the contact size increases. The theor y also explains this behavior.