Magnetization of small arrays of interacting single-domain particles

We have prepared tailored small arrays of single-domain Ni nanomagnets exhi biting an easy-axis perpendicular to the substrate surface. Using ballistic Hall micromagnetometry we probe the magnetization under different tilt ang les. For an array of 13 nanomagnets with 700 nm spacing, we observe distinc t plateau values in the hysteresis loop indicating the stepwise switching o f these particles. The observed hierarchy of reversal comes close to a mode l on the basis of the magnetostatic interparticle interaction. (C) 1999 Ame rican Institute of Physics. [S0021-8979(99)69608-6].