Interface reactions in Ta/Ni81Fe19/Ta structures and their influence on magnetic properties

• Published in: Thin solid films 2005-07, Vol.484 (1-2), p.208-214
• Main Authors: YU, G. H, LI, M. H, TENG, J, ZHU, F. W, LAI, W. Y
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Giant magnetoresistance; Interfacial magnetic properties (multilayers, magnetic quantum wells, superlattices, magnetic heterostructures); Magnetic properties and materials; Magnetic properties of surface, thin films and multilayers; Magnetotransport phenomena, materials for magnetotransport; Physics
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2005.02.031

Ta/Ni81Fe19, Ni81Fe19/Ta, Cu/Ni81Fe19, and Ni81Fe19/Cu structures are commonly used in the magnetic multilayers with giant magnetoresistance. For a Ta/Ni81Fe19/Ta fundamental structure, Ta seed and Ta cap layers result in a loss of moment equivalent to a magnetically dead layer of thickness 1*6+/--0*2 nm. Experimental results show that a chemical reaction between Ta and Ni81Fe19 takes place at the Ta/Ni81Fe19 and Ni81Fe19/Ta interfaces. The thickness of the magnetically dead layer was significantly reduced by the insertion of a small amount of Bi in the Ta/Ni81Fe19 /Ta structure (i.e. Ta/Bi/Ni81Fe19/Ta). This result indicates that Bi acts as a surfactant that can suppress the interface reaction in multilayers. For a Cu/Ni81Fe19/Cu film, permalloy layers have hardly lost their magnetic moment since interface reactions at the Cu/Ni81Fe19 interface or Ni81Fe19/Cu interface hardly occurs.