HEAD-TO-HEAD DOMAIN-WALL STRUCTURES IN THIN MAGNETIC STRIPS

We present calculations of head to head domain wall structures in magn etic strips of Ni80Fe20 with widths, w, ranging from 75 nm to 500 nm a nd thicknesses, t, from 1 nm to 64 nm, Neglecting magnetocrystalline a nd magnetostrictive anisotropy energies, minimization of exchange and magnetostatic energy leads to one of two types of domain wall structur es: 'transverse' walls with magnetization at the center of the wall di rected transverse to the strip axis and 'vortex' walls where the magne tization forms a vortex at the center of the wall, Calculation of the domain wall energies leads to a proposed phase diagram for head to hea d domain walls where transverse walls have lower energy when dimension s are less than t(crit)w(crit) approximate to 130A/mu(0)M(s)(2).