Abstract
By using first order reversal curves (FORCs), we reveal distinct magnetization reversal behavior in the CoPtCr films with different oxide additives, including Ta 2 O 5 , SiO 2 and their mixtures. Increasing the ratio of Ta 2 O 5 -to-SiO 2 alters the inter-grain interaction from an exchange coupling (parallel) to a dipolar-field coupling (anti-parallel). During the sputtering process, the Ta 2 O 5 additives release extra oxygen to induce the formation of CrO x , observed from X-ray absorption spectroscopy. The reduced grain-to-grain exchange coupling strength by increasing Ta 2 O 5 additives could be attributed to the increased volume concentration of oxides and/or the presence of the CrO x . © 2012 American Institute of Physics.