TY - JOUR

T1 - Simple analysis for frequency increase in spin torque oscillation

AU - Mitsumata, Chiharu

AU - Tomita, Satoshi

AU - Seki, Takeshi

AU - Mizuguchi, Masaki

N1 - Funding Information:
This work was supported in part by a Grant-in-Aid for Scientific Research (23360004) from the Japan Society for the Promotion of Science.

PY - 2012

Y1 - 2012

N2 - The spin torque oscillation (STO) due to magnetic resonance is investigated in term of the Landau-Lifshitz-Gilbert (LLG) equation. An analytic formula of the LLG equation with macro-spins describes a spin state that involves information of an oscillation frequency. The LLG equation can be transformed into an equation of a forced oscillation. The obtained equation includes a frequency of STO, an effective Gilbert damping factor, and an injected spin current.We show that the effective Gilbert damping is given by a linear function of the spin current. Contrastingly, the frequency of STO is not affected by the injected spin current. However, the time-dependent variation of the spin current, e.g., the pulsated spin current, possibly increases the frequency of STO.

AB - The spin torque oscillation (STO) due to magnetic resonance is investigated in term of the Landau-Lifshitz-Gilbert (LLG) equation. An analytic formula of the LLG equation with macro-spins describes a spin state that involves information of an oscillation frequency. The LLG equation can be transformed into an equation of a forced oscillation. The obtained equation includes a frequency of STO, an effective Gilbert damping factor, and an injected spin current.We show that the effective Gilbert damping is given by a linear function of the spin current. Contrastingly, the frequency of STO is not affected by the injected spin current. However, the time-dependent variation of the spin current, e.g., the pulsated spin current, possibly increases the frequency of STO.

KW - Forced oscillation

KW - Landau-Lifshitz-Gilbert equation

KW - Magnetic resonance

KW - Spin torque

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U2 - 10.1109/TMAG.2012.2201700

DO - 10.1109/TMAG.2012.2201700

M3 - Article

AN - SCOPUS:84867837707

VL - 48

SP - 3955

EP - 3957

JO - IEEE Transactions on Magnetics

JF - IEEE Transactions on Magnetics

SN - 0018-9464

IS - 11

M1 - 6332855

ER -