A Lagrangian formalism is used to find steady-state solution of the Landau–Lifshitz–Gilbert–Slonczewski equation corresponding to the linear autonomous dynamics of a magnetic auto-oscillatory system subject to the action of a spin-polarized electric current. In such a system, two concurrent dissipative mechanisms, arising from the positive intrinsic dissipation and the negative current-induced one, take place simultaneously and make the excitation of a steady precessional motion of the magnetization vector conceivable. The proposed formulation leads to the definition of a complex generalized non-Hermitian Eigenvalue problem, both in the case of a macrospin model and in the more general case of an ensemble of magnetic particles interacting each other through magnetostatic and exchange interactions. This method allows to identify the spin-wave normal modes which become unstable in the presence of the two competing dissipative contributions and provides an accurate estimation of the value of the excitation threshold current.
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Data di pubblicazione: | 2011 | |
Titolo: | Lagrangian formulation of the linear autonomous magnetization dynamics in spin-torque auto-oscillators | |
Autori: | G. Consolo; G. Gubbiotti; L. Giovannini; R. Zivieri | |
Rivista: | APPLIED MATHEMATICS AND COMPUTATION | |
Parole Chiave: | Autonomous dynamics; Auto-oscillators; Complex generalized non-Hermitian Eigenproblem; Lagrange equations; Landau–Lifshitz–Gilbert equation; Micromagnetics; Rayleigh dissipation function; Spin-transfer torque | |
Abstract: | A Lagrangian formalism is used to find steady-state solution of the Landau–Lifshitz–Gilbert–Slonczewski equation corresponding to the linear autonomous dynamics of a magnetic auto-oscillatory system subject to the action of a spin-polarized electric current. In such a system, two concurrent dissipative mechanisms, arising from the positive intrinsic dissipation and the negative current-induced one, take place simultaneously and make the excitation of a steady precessional motion of the magnetization vector conceivable. The proposed formulation leads to the definition of a complex generalized non-Hermitian Eigenvalue problem, both in the case of a macrospin model and in the more general case of an ensemble of magnetic particles interacting each other through magnetostatic and exchange interactions. This method allows to identify the spin-wave normal modes which become unstable in the presence of the two competing dissipative contributions and provides an accurate estimation of the value of the excitation threshold current. | |
Digital Object Identifier (DOI): | 10.1016/j.amc.2011.02.043 | |
Handle: | http://hdl.handle.net/11392/1434310 | |
Appare nelle tipologie: | 03.1 Articolo su rivista |