Investigations on magnetic properties in ultrathin single crystal Fe rectangular arrays patterned by selective wet-etching

The magnetic properties of the rectangular element arrays of the ultrathin epitaxial Fe films on GaAs (100) have been studied with focused magneto-optical Kerr effect and ferromagnetic resonance. The coercivity increases upon decreasing aspect ratio of the elements. When the magnetic field is along the [0-11] direction of the GaAs substrate, which is the long edge of the element, a high remanent ratio of all the hysteresis loops is shown, indicating a global magnetic easy axis and a single domain remanent state, while along the [001] direction the breakage of the single domain remanent state occurs for the element with the aspect ratio lower than 2. These results are attributed to the competition among the intrinsic anisotropies, the demagnetizing field, and interelement dipole coupling as determined by the ferromagnetic resonance measurements. (C) 2011 American Institute of Physics. [doi:10.1063/1.3556764]