Apparent permeability of ordered magnetically soft nanowire arrays

Using the equivalent 2D model for finite element method (FEM) we calculated apparent permeability µa and demagnetization factor D for permalloy nanowire and microwire arrays. The simulation results were verified by 3D FEM for arrays up to 3000 wires and experimentally for very large arrays containing up to 40 million wires. We achieved µa = 3 to 33 and coercivities Hc = 1 to 9 kA/m, which are low values for wire arrays. The µa depends mainly on the array geometry; it can be increased by increasing the distance between wires (pitch) and the wire length-to-diameter ratio L/d.