2006/02/28 by J-M. L. Beaujour, J. H. Lee, A. D. Kent +5 · 51 citations
Engineering · Materials Science · Physics and Astronomy · #Anisotropy #Condensed matter physics #Crystallite #Ferromagnetic resonance #Ferromagnetism #Magnetic Properties and Applications #Magnetic anisotropy #Magnetic field #Magnetic properties of thin films #Magnetization #Materials science #Metallic Glasses and Amorphous Alloys #Optics #Physics #Relaxation (psychology) #cond-mat.mes-hall
paper · pdf · doi:10.1103/physrevb.74.214405
published in Physical Review B 74(21) (American Physical Society)
arxiv created 2006/06/14 · openalex publication_date 2006/12/05 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
The magnetic properties and magnetization dynamics of polycrystalline ultrathin Co layers were investigated using a broadband ferromagnetic resonance technique at room temperature. A variable-thickness (1\phantom\rule0.3em0exnm\ensuremath\leqslantt\ensuremath\leqslant10\phantom\rule0.3em0exnm) Co layer is sandwiched between 10\text\ensuremath-nm-thick Cu layers (10\phantom\rule0.3em0exnm Cu\ensuremath|t\phantom\rule0.3em0exCo\ensuremath|10\phantom\rule0.3em0exnm Cu), while materials in contact with the Cu outer interfaces are varied to determine their influence on the magnetization damping. The resonance field and the linewidth were studied for in-plane magnetic fields in field-swept experiments at a fixed frequency, from 4\phantom\rule0.3em0exto\phantom\rule0.3em0ex25\phantom\rule0.3em0exGHz. The Co layers have a lower magnetization density than the bulk and an interface contribution to the magnetic anisotropy normal to the film plane. The Gilbert damping, as determined from the frequency dependence of the linewidth, increases with decreasing Co layer thickness for films with outer Pt layers. This enhancement is not observed in structures without Pt layers. The result can be understood in terms of a nonlocal contribution to the damping due to spin pumping from Co through the Cu layer and spin relaxation in Pt layers. Pt layers just 1.5\phantom\rule0.3em0exnm thick are found to be sufficient to enhance the damping and thus act as efficient ``spin sinks.'' In structures with Pt outer layers, this nonlocal contribution to the damping becomes predominant when the Co layer is thinner than 4\phantom\rule0.3em0exnm.