skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Magnetization Damping in Ultrathin Polycrystalline Co Films: Evidence for Nonlocal Effects

Abstract

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 nm{center_dot}t{center_dot}10 nm) Co layer is sandwiched between 10-nm-thick Cu layers (10 nm Cu|t Co|10 nm 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 to 25 GHz. 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 nm thick are found to be sufficient to enhance the damping and thus act as efficient 'spin sinks'. In structures with Pt outermore » layers, this nonlocal contribution to the damping becomes predominant when the Co layer is thinner than 4 nm.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
930604
Report Number(s):
BNL-80910-2008-JA
Journal ID: ISSN 1098-0121; TRN: US200904%%613
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review B: Condensed Matter and Materials Physics; Journal Volume: 74
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; COBALT; THIN FILMS; POLYCRYSTALS; MAGNETIC PROPERTIES; MAGNETIZATION; SPIN; COPPER; PLATINUM; LAYERS; national synchrotron light source

Citation Formats

Beaujour,J., Lee, J., Kent, A., Krycka, K., and Kao, C. Magnetization Damping in Ultrathin Polycrystalline Co Films: Evidence for Nonlocal Effects. United States: N. p., 2006. Web. doi:10.1103/PhysRevB.74.214405.
Beaujour,J., Lee, J., Kent, A., Krycka, K., & Kao, C. Magnetization Damping in Ultrathin Polycrystalline Co Films: Evidence for Nonlocal Effects. United States. doi:10.1103/PhysRevB.74.214405.
Beaujour,J., Lee, J., Kent, A., Krycka, K., and Kao, C. Sun . "Magnetization Damping in Ultrathin Polycrystalline Co Films: Evidence for Nonlocal Effects". United States. doi:10.1103/PhysRevB.74.214405.
@article{osti_930604,
title = {Magnetization Damping in Ultrathin Polycrystalline Co Films: Evidence for Nonlocal Effects},
author = {Beaujour,J. and Lee, J. and Kent, A. and Krycka, K. and Kao, C.},
abstractNote = {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 nm{center_dot}t{center_dot}10 nm) Co layer is sandwiched between 10-nm-thick Cu layers (10 nm Cu|t Co|10 nm 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 to 25 GHz. 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 nm 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 nm.},
doi = {10.1103/PhysRevB.74.214405},
journal = {Physical Review B: Condensed Matter and Materials Physics},
number = ,
volume = 74,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}