Spin waves (SWs) have became the subject of an intense theoretical and experimental investigation due to ‎their potentiality as dissipationless information carriers for spintronic logic gates and waveguides. ‎Differently from the Fourier analysis of a system’s magnetic response after proper excitation, the ‎Hamiltonian approach [1] allows the computation of the whole set of SW modes, independently ‎of the excitation symmetry and action, as an eigenvalue/eigenvector problem; moreover, the ‎modes can be in principle computed arbitrarily close to the critical field for any magnetization ‎change (“transition”), e.g. magnetization reversal, vortex-to saturation transition, etc. The last property is ‎particularly suitable to the calculation of soft modes [2], i.e. SWs with a frequency going to zero ‎at the critical field: at the critical field, this modes are known to trigger the transition by ‎transferring their symmetry to the static magnetization, determining a specific instability that ‎leads the system to reconfigure in a different way. Besides the theoretical interest in describing ‎many kind of changes of the magnetization configuration, soft modes have surprising properties of ‎great importance for spintronics, as a asymmetric broadening of their bandwidth [3] (with different ‎group velocity in different directions), and for a dynamic explanation of the complexity of reversal ‎avalanches (Dirac strings) in macrospin networks like artificial quasicrystals and artificial spin ices [4]. [1] L. Giovannini, F. Montoncello and F. Nizzoli, Phys. Rev B 75, 024416 (2007) [2] F. Montoncello et al., Phys. Rev. B 77, 214402 (2008) [3] F. Montoncello and L. Giovannini, Appl. Phys. Lett. 104, 242407 (2014) [4] F. Montoncello et al., Journal of Magnetism and Magnetic Materials 423, 158 (2017).

Softening of spin waves calculated under a Hamiltonian approach: importance for information delivery, and in the understanding of reversal avalanches in macrospin networks

MONTONCELLO, Federico
2017

Abstract

Spin waves (SWs) have became the subject of an intense theoretical and experimental investigation due to ‎their potentiality as dissipationless information carriers for spintronic logic gates and waveguides. ‎Differently from the Fourier analysis of a system’s magnetic response after proper excitation, the ‎Hamiltonian approach [1] allows the computation of the whole set of SW modes, independently ‎of the excitation symmetry and action, as an eigenvalue/eigenvector problem; moreover, the ‎modes can be in principle computed arbitrarily close to the critical field for any magnetization ‎change (“transition”), e.g. magnetization reversal, vortex-to saturation transition, etc. The last property is ‎particularly suitable to the calculation of soft modes [2], i.e. SWs with a frequency going to zero ‎at the critical field: at the critical field, this modes are known to trigger the transition by ‎transferring their symmetry to the static magnetization, determining a specific instability that ‎leads the system to reconfigure in a different way. Besides the theoretical interest in describing ‎many kind of changes of the magnetization configuration, soft modes have surprising properties of ‎great importance for spintronics, as a asymmetric broadening of their bandwidth [3] (with different ‎group velocity in different directions), and for a dynamic explanation of the complexity of reversal ‎avalanches (Dirac strings) in macrospin networks like artificial quasicrystals and artificial spin ices [4]. [1] L. Giovannini, F. Montoncello and F. Nizzoli, Phys. Rev B 75, 024416 (2007) [2] F. Montoncello et al., Phys. Rev. B 77, 214402 (2008) [3] F. Montoncello and L. Giovannini, Appl. Phys. Lett. 104, 242407 (2014) [4] F. Montoncello et al., Journal of Magnetism and Magnetic Materials 423, 158 (2017).
978-83-937270-5-6
spin waves, magnonic crystals, soft modes, information delivery, dissipationless technology
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11392/2377144
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