Asymmetric exchange bias in NiFe/FeMn/NiFe multilayer films

Abstract Exchange bias in the two interfaces of NiFe/FeMn/NiFe films is investigated. The lower NiFe shows smaller coercivity and larger exchange shift than those of upper NiFe, respectively. As the FeMn thickness become thicker and thicker, upper interface roughness increases and exchange bias decreases. When the thickness of FeMn is less than 7 nm, the roughness of top surface of FeMn is maintained with the same level of the bottom interface, and top and bottom NiFe layers shows little difference in coercivity and exchange bias.