The basic purpose of this study is to optimize the patterning method in terms of Block Copolymer (BCP) to magnetic materials in fabrication process. By producing anti-dots (holes) in the magnetic film to create nanopaths, electrons could transport through the nanochannels created by cylindrical nanoholes. The patterning apparently affects magnetism characteristic and microstructure of the magnetic materials. In addition, magnetoresistance is the tendency of a material to change electrical resistance depending on an incident magnetic field. Colossal magnetoresistance phenomenon happens on a chemically homogeneous substance has small (~ 3 nm) ferromagnetic regions, but is otherwise not ferromagnetic.