Non-Gilbert-type damping of the magnetic relaxation in ultrathin ferromagnets: Importance of magnon-magnon scattering

Lindner, J.; Lenz, K.; Kosubek, E.; Baberschke, K.; Spoddig, D.; Meckenstock, R.; Pelzl, J.; Frait, Z.; Mills, D. L.

doi:10.1103/physrevb.68.060102

Cited by 120 publications

(79 citation statements)

References 26 publications

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“…In general, two-magnon spin wave scattering by impurities may exist in our measurements at all field ranges 32,33 , not only near Hkeff as suggested in the discussion of the previous section 32,33 . The resultant additional linewidth broadening would then be regarded as an extrinsic contribution to the damping [34][35][36] .…”

Section: Considerations Of Two-magnon Scatteringmentioning

confidence: 83%

Determination of intrinsic damping of perpendicularly magnetized ultrathin films from time-resolved precessional magnetization measurements

et al. 2015

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Abstract:Magnetization dynamics are strongly influenced by damping, namely the loss of spin angular momentum from the magnetic system to the lattice. An "effective" damping constant αeff is often determined experimentally from the spectral linewidth of the free induction decay of the magnetization after the system is excited to its non-equilibrium state. Such an αeff, however, reflects both intrinsic damping as well as inhomogeneous broadening that arises, for example, from spatial variations of the anisotropy field. In this paper we compare measurements of the magnetization dynamics in ultrathin non-epitaxial films having perpendicular magnetic anisotropy using two different techniques, timeresolved magneto optical Kerr effect (TRMOKE) and hybrid optical-electrical ferromagnetic resonance (OFMR). By using an external magnetic field that is applied at very small angles to the film plane in the TRMOKE studies, we develop an explicit closedform analytical expression for the TRMOKE spectral linewidth and show how this can be used to reliably extract the intrinsic Gilbert damping constant. The damping constant determined in this way is in excellent agreement with that determined from the OFMR method on the same samples. Our studies indicate that the asymptotic high-field approach that is often used in the TRMOKE method to distinguish the intrinsic damping from the 2 effective damping may result in significant error, because such high external magnetic fields are required to make this approach valid that they are out of reach. The error becomes larger the lower is the intrinsic damping constant, and thus may account for the anomalously high damping constants that are often reported in TRMOKE studies. In conventional ferromagnetic resonance (FMR) studies, inhomogeneous contributions can be readily distinguished from intrinsic damping contributions from the magnetic field dependence of the FMR linewidth. Using the analogous approach, we show how reliable values of the intrinsic damping can be extracted from TRMOKE in two distinct magnetic systems with significant perpendicular magnetic anisotropy: ultrathin CoFeB layers and Co/Ni/Co trilayers.3

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Section: Considerations Of Two-magnon Scatteringmentioning

confidence: 83%

Determination of intrinsic damping of perpendicularly magnetized ultrathin films from time-resolved precessional magnetization measurements

et al. 2015

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“…This field changes its sign when the magnetization is half way ( M ʈ ͗110͘ Fe ) between parallel and perpendicular orientations with respect to the defects. A similar argument was recently used by Lindner et al 10 to explain the absence of two magnon scattering along the ͗110͘ directions on Fe/V superlattices. Therefore the following ansatz: I(q, M )ϭQ(q)• cos 2 (2 M ) is appropriate to interpret the FMR linewidth.…”

Section: Discussionmentioning

confidence: 71%

Spin dynamics in ultrathin film structures with a network of misfit dislocations

Woltersdorf

Heinrich

Woltersdorf

et al. 2004

Journal of Applied Physics

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Using ferromagnetic resonance ͑FMR͒ and transmission electron microscopy we studied the structural and magnetic properties of lattice mismatched magnetic ultrathin multilayers of the system Au/Fe/Au/Pd/Fe͑001͒ prepared on GaAs͑001͒. We observed a correlation between the periodic lattice irregularities due to the misfit accommodation processes and the resulting magnetic properties of the multilayer system: In samples with a network of misfit dislocations the FMR measurements have shown that a significant part of the damping is extrinsic and caused by two magnon scattering. The angular dependence of the FMR linewidth reflects the in-plane symmetry of the dislocation arrangement.

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“…Finally, we show that for a joined interpretation by theory and experiment in nanomagnetism one must either extrapolate the experimental observables back to T = 0, or include T = 0 in theory. In that case electronic band structure effects, smearing at the Fermi edge, seems to be a minor effect; most important are spin wave excitations and magnon-magnon scattering [30]. In Sec.2 we discussed the MAE and importance of orbital magnetism, in Sec.3 thermal spin wave excitations were added to understand J inter (T).…”

Section: Discussionmentioning

confidence: 99%

Non-Gilbert-type damping of the magnetic relaxation in ultrathin ferromagnets: Importance of magnon-magnon scattering

Cited by 120 publications

References 26 publications

Determination of intrinsic damping of perpendicularly magnetized ultrathin films from time-resolved precessional magnetization measurements

Determination of intrinsic damping of perpendicularly magnetized ultrathin films from time-resolved precessional magnetization measurements

Spin dynamics in ultrathin film structures with a network of misfit dislocations

Magnetic anisotropy energy and interlayer exchange coupling in ultrathin ferromagnets: Experiment versus theory

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