About the dipolar approach in magnetostatically coupled bistable magnetic micro and nanowires

The dipolar approximation has been recently considered in order to account for the magnetostatic interaction in arrays of bistable magnetic micro and nanowires of several diameters. But this approximation fails for short distances between wires. An exact calculation of the multipolar components of the field created by homogeneously magnetized cylinders has been performed, finding that nondipolar contributions are not negligible for typical distances considered in experiments. The length and diameter of individual wires, and separating distance between them, can be tailored to reach convenient values of interacting field and consequently of switching of magnetization reversal.