Magnetic properties and interactions of single-domain nanomagnets in a periodic array

Macroscopic and microscopic switching characteristics are obtained for 100 nm period arrays of Ni nanomagnets with a mean switching field (coercive field) of 710 Oe. Magnetic force microscopy in combination with micromagnetic theory shows that inhomogeneities in the particle shapes result in an intrinsic standard deviation in switching fields of 105 Oe, while the interactions between neighboring nanomagnets broaden the distribution to 276 Oe, equivalent to a squareness of 0.8 in the bulk hysteresis loop. The switching field distribution is consistent with curling as the switching mechanism. (C) 2001 American Institute of Physics.