Magnetization and Magnetic Anisotropy of Co/W Multilayers

• Published in: Physica Status Solidi (b) (Germany) 2001-06, Vol.225 (2), p.449-457
• Main Authors: Spasova, M., Wiedwald, U., Ramchal, R., Farle, M., Jergel, M., Majkova, E., Luby, S., Senderak, R.
• Format: Article
• Language: English
• Subjects: 68.35.Ct; 75.30.Gw; 75.70.Ak; 75.70.Rf; 76.50.+g; Applied sciences; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Interfacial magnetic properties (multilayers, magnetic quantum wells, superlattices, magnetic heterostructures); Magnetic properties and materials; Magnetic properties of surface, thin films and multilayers; Metals. Metallurgy; Physics; S1.2
• ISSN: 0370-1972; 1521-3951
• DOI: 10.1002/1521-3951(200106)225:2<449::AID-PSSB449>3.0.CO;2-3

The magnetic properties of polycrystalline Co/W multilayers have been investigated using angular‐dependent ferromagnetic resonance (FMR) and SQUID magnetometry. Two sets of samples with a constant thickness of Co layers (CoI: dCo = 1 nm and CoII: dCo = 2.5 nm) and varying W layer thickness (1 to 7 nm) were studied. The structure of the multilayers was analysed by X‐ray reflectivity (XRR) and X‐ray diffraction (XRD). We found a well‐defined 〈110〉 texture and coherent structure of the multilayers. The saturation magnetization of Co is smaller than that of bulk Co which is explained by a reduced Co moment at the interfaces of more than 50%. A narrow FMR linewidth on the order of 200 Oe at 9.5 GHz is observed for CoI and CoII multilayers with dW ≈ 1 nm that indicates the high magnetic homogeneity of the Co layers. The second and fourth‐order magnetic anisotropy constants (K2, K4⟂) are found to be independent of the Co layer thickness. K2 is inversely proportional to the W layer thickness, which is due to the changing lateral lattice mismatch with the W layers.