Low temperature magnetic force microscope study of magnetization reversal in patterned nanoislands of SrRuO3

SrRuO3 is an itinerant ferromagnet (T-c similar to 150 K) characterized by large uniaxial magnetocrystalline anisotropy (K-1 similar to 7.7 x 10(6) erg/cm(3)) and relatively low saturation magnetization (M-s = 213 emu/cm(3)) - properties which make SrRuO3 an extremely hard magnetic material. We have patterned arrays of rectangular nanoislands of a high quality epitaxial film of SrRuO3 with sides ranging between 50 and 500 nm, and studied their magnetization reversal at 4 K using a low temperature magnetic force microscope. We find that the nucleation field for many of the nanoislands is very close to that expected by the Stoner-Wohlfarth model (similar to 3.8 T) and from nanoislands which exhibit partial reversals we can determine an upper bound for the nucleation volume on the order of 100 x 100 x 10 nm(3). We also find that domain wall pinning in the nanoislands is extremely high and in some cases the depinning field exceeds similar to 3 T. (C) 2012 American Institute of Physics. [doi:10.1063/1.3673827]