Domain Walls in a Dipole-Coupled Transverse Magnetic Island Chain

I analyze the nonlinear Hamiltonian equations of motion for a one-dimensional chain of transverse magnetic nano-islands, seeking solutions for different types of static domain walls (DWs) connecting uniform static states. The system of elongated magnetic islands oriented transverse (y-direction) to the chain direction (x-direction) experiences an applied magnetic field transverse to the chain. The macro-spin model includes dipole interactions between islands, their uniaxial and easy-plane anisotropies, and Oersted energy of the applied field. DWs can form most easily between pairs of degenerate uniform states, described by their local magnetizations as oblique, y-parallel, and y-alternating. The DWs between oblique states are well described with scalar φ4 theory. General DW structures are found via a numerical energy relaxation scheme. At some anisotropy and field parameters, nearest-neighbor dipole interactions drive antiferromagnetic order inside the DW itself.