RETRACTED: Effect of Ta on magnetic thicknesses of permalloy (Ni81Fe19) films (Retracted Article)

Effect of Ta and Cu seed layers, as well as Ta and Cu cap layers on the effective magnetic thickness of ultrathin permalloy (Ni81Fe19) were experimentally investigated for magnetic random access memory applications. The films were deposited by magnetron sputtering. For a Ta/Ni81Fe19/Ta fundamental structure, Ta seed and Ta cap layers resulted in a loss of moment equivalent to a magnetically dead layer of thickness 1.6 +/- 0.2 nm. X-ray photoelectron spectroscopy shows that a chemical reaction takes place at the Ta/Ni81Fe19 and Ni81Fe19/Ta interfaces, i.e. 2Ta + Ni = NiTa2, which is thermodynamically favourable. For the Cu/Ni81Fe19/Cu film, permalloy layers have hardly lost magnetic moment due to a lack of interface reactions in the Cu/Ni81Fe19 interface and Ni81Fe19/Cu interface.