Magnetic Domain Walls in Double Exchange Materials

Abstract

We study magnetic domain walls in double exchange materials. The domain wall width is proportional to the square root of the stiffness. In the double exchange model the stiffness has two terms: the kinetic energy and the Hartree term. The kinetic energy term comes from the decrease of the tunneling amplitude in the domain wall region. The Hartree term appears only in double exchange materials and it comes from the connection between band-width and magnetization. We also calculate the low-field magnetoresistance associated with the existence of magnetic domains. We find a magnetoresistance of 1-2%. The magnetoresistance c an be considerably larger in magnetically constrained nanocontacts.