Asymmetric magnetization reversal in exchange-biased NiFe∕CoO submicron-sized structures

Abstract

Exchange coupling in patterned exchange-biased NiFe∕CoO squares with different sizes has been studied. Arrays of square dots with the lateral size varying between 300 and 900nm and a fixed interdot distance of 800nm were prepared by sputtering followed by in situ oxidation. Exchange bias in the initial and trained loops was studied as a function of the size, temperature, and cooling field. A decrease in the exchange bias shift was observed with a decreasing size, which might be due to the magnetostatic interdots interaction. For the trained loops, a variation of exchange bias with the temperature and cooling field, similar to those observed in continuous films, was observed.