GMR in DC magnetron sputtered Ni81Fe19/Cu multilayers

In this paper, we present results of a study on Ni₈₁Fe ₁₉Cu MLs deposited using a four-source DC magnetron sputtering system operated in planetary mode. A significant change of GMR value with deposition conditions, especially base pressure and deposition pressure, has been observed for Ni₁₈Fe₁₉/Cu MLs. With an optimized process, we have obtained a GMR response of 9.5% with a field sensitivity of 0.44%/Oe for Si/[(Ni₈₁Fe₁₉)17 Å/Cu20 Å]₂₀ MLs without an Fe buffer layer. The insertion of a very thin layer of a second magnetic species at nonmagnetic/magnetic interfaces in the ML stack makes GMR response either sensitive or less sensitive to deposition conditions depending on the species selected. We believe that the key to obtaining large GMR values in Ni₈₁Fe ₁₉/Cu MLs lies in the control of layered structure and interfacial chemistry. In addition, these Ni₈₁Fe₁₉/Cu MLs survive high temperature annealing up to 250°C, retaining a GMR value of 8.5%. The thermal stability exhibited by these MLs over the temperature range for device fabrication makes them valuable for high density recording head sensor applications