Simple analysis for frequency increase in spin torque oscillation

Chiharu Mitsumata; Satoshi Tomita; Takeshi Seki; Masaki Mizuguchi

doi:10.1109/TMAG.2012.2201700

Simple analysis for frequency increase in spin torque oscillation

Chiharu Mitsumata, Satoshi Tomita, Takeshi Seki, Masaki Mizuguchi

Research output: Contribution to journal › Article › peer-review

1 Citation (Scopus)

Abstract

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.

Original language	English
Article number	6332855
Pages (from-to)	3955-3957
Number of pages	3
Journal	IEEE Transactions on Magnetics
Volume	48
Issue number	11
DOIs	https://doi.org/10.1109/TMAG.2012.2201700
Publication status	Published - 2012

Keywords

Forced oscillation
Landau-Lifshitz-Gilbert equation
Magnetic resonance
Spin torque

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
Electrical and Electronic Engineering

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10.1109/TMAG.2012.2201700

Cite this

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title = "Simple analysis for frequency increase in spin torque oscillation",

abstract = "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.",

keywords = "Forced oscillation, Landau-Lifshitz-Gilbert equation, Magnetic resonance, Spin torque",

author = "Chiharu Mitsumata and Satoshi Tomita and Takeshi Seki and Masaki Mizuguchi",

note = "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.",

year = "2012",

doi = "10.1109/TMAG.2012.2201700",

language = "English",

volume = "48",

pages = "3955--3957",

journal = "IEEE Transactions on Magnetics",

issn = "0018-9464",

publisher = "Institute of Electrical and Electronics Engineers Inc.",

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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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JO - IEEE Transactions on Magnetics

JF - IEEE Transactions on Magnetics

IS - 11

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Simple analysis for frequency increase in spin torque oscillation

Abstract

Keywords

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