AVS 50th International Symposium
    Magnetic Interfaces and Nanostructures Thursday Sessions
       Session MI-ThA

Paper MI-ThA8
Weak Spin Pumping and Inhomogeneity in Cr/NiFe/Cr Trilayers

Thursday, November 6, 2003, 4:20 pm, Room 316

Session: Magnetization Dynamics
Presenter: R.D. McMichael, National Institute of Standards and Technology
Authors: R.D. McMichael, National Institute of Standards and Technology
A.J. Shapiro, National Institute of Standards and Technology
A.P. Chen, National Institute of Standards and Technology
W.F. Egelhoff, National Institute of Standards and Technology
Correspondent: Click to Email
Ferromagnetic resonance linewidth measurements on 10 nm Cr/5 nm Ni@sub 80@Fe@sub 20@/10 nm Cr trilayers show that Cr does not contribute significantly to the damping properties of NiFe. In contrast, measurements in Pt/NiFe/Pt and Pd/NiFe/Pd trilayers have demonstrated strong "spin pumping" enhancements due to the normal metal layers.@footnote 1@ The experiments described here were designed to determine whether similar spin-pump damping effects were likely in CoCr recording media due to the presence of Cr in grain boundaries. We found that the linewidth in Cr/NiFe/Cr trilayers was large relative to Cu/NiFe/Cu trilayers. To discern the origins of the enhanced line width, Cu spacer layers were included between the NiFe layer and either the bottom or top Cr layer and an analysis of the angular dependence of the line width was performed. The results show that the linewidth increase is associated with inhomogeneity at the bottom Cr/NiFe interface. The inhomogenitey at this interface may be a reflection of the growth beginning as bcc-NiFe on bcc-Cr and converting to fcc-NiFe. Growth of Cr on NiFe had an insignificant effect on the linewidth of the NiFe. These conclusions were confirmed by MOIF imaging of the magnetization reversal, which showed nucleation and growth of reversed domains in NiFe on Cr, but which showed low coercivity motion of a single domain wall sweeping out the entire area when the NiFe was deposited on Cu, whether the cap layer was Cu or Cr. @FootnoteText@ @footnote 1@ S. Mizukami, Y. Ando and T. Miyazaki, Jpn. J. Appl. Phys., v. 40, pp. 580-585 (2001).