The Suppression of Orange-Peel Coupling in Magnetic Tunnel Junctions by Pre-Oxidation
William F. Egelhoff Jr., Robert McMichael, Cindi L. Dennis, Mark D. Stiles, Alexander J. Shapiro, Brian B. Maranville, Cedric J. Powell
We have have found that pre-oxidation of the bottom Co electrode in magnetic tunnel junctions (MTJs) very effectively suppresses orange-peel coupling. The result is a free layer that is much softer. Work by others has demonstrated that pre-oxidation is compatible with high-quality MTJ fabrication.A few years ago, it was reported that pre-oxidation of the bottom Co electrode in magnetic tunnel junctions could dramatically suppress the intermixing that occurs when Al is deposited on Co. It was also found that this pre-oxidation procedure not only increased the tunneling magnetoresistance (TMR) but dramatically reduced the scatter of data points in a plot of TMR versus R A product, where R is the resistance of the MTJ and A is the tunneling area. The observation that pre-oxidation suppresses intermixing has been confirmed and extended in recent work. Also reported a few years ago was the observation that in GMR spin valves, the oxidation of the surface of the top Co layer suppressed magnetic poles at bumps in the surface. The data suggested that bumps oxidize first and the system self-passivates as a flat oxide-metal interface forms. In light of these observations, it seemed likely that pre-oxidation of the bottom Co electrode in MTJs might be an effective way of suppressing orange-peel coupling.
Journal of Applied Physics
magnetic tunnel junctions, orange peel coupling, pre-oxidation
Egelhoff Jr., W.
, McMichael, R.
, Dennis, C.
, Stiles, M.
, Shapiro, A.
, Maranville, B.
and Powell, C.
The Suppression of Orange-Peel Coupling in Magnetic Tunnel Junctions by Pre-Oxidation, Journal of Applied Physics
(Accessed December 2, 2023)