Stripe to "spin-quantum well" formation and collective spin reorientation in self-assembled Ni nanomagnets on GaN

We report domain formation and spin phase transition in annealing induced self-assembled Ni nanodots on GaN with size distribution greater than the exchange length. The as-deposited Ni film shows stripelike magnetic domains. The enclosed spin well phase occurs due to annealed induced structural transition in the films. The reorientation occurs only at the center of the island. We also observed the magnetic correlation length remains constant during the structural phase change despite spin reorientation. The magnetic correlation length is destroyed for well-formed nanodots.