Magnetic bubbles and domain evolution in Fe/Gd multilayer nanodots

The formation of magnetic bubbles and the domain-evolution processes, induced by a perpendicular magnetic field in Fe/Gd multilayer films and nanodots, have been investigated. At room temperature, the stripe domains in a continuous film transform into magnetic bubbles in an external field, while bubbles form spontaneously in nanodots due to the existence of shape anisotropy. When the temperature decreases to 20 K, the enhancement of the perpendicular magnetic anisotropy of the samples results in an increase of the domain size in the continuous film and the magnetization-reversal behavior of each nanodot becomes independent, and most reversed dots do not depend on each other, indicating the magnetic characteristics of a single domain. The present research provides further understanding of the evolution of magnetic bubbles in the Fe/Gd system and suggests their promising applications in patterned recording materials.