Head to head domain wall structures in thin magnetic strips

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