Magnetization precession by short-wavelength magnon excitations and spin-transfer torque

Qiao, Shan; Shen, Yan; Kang, Shishou; Li, Qiang; Qin, Yu-Feng; Zhao, Yinrui; Zhang, Zhe; Liu, Shuqing

doi:10.1103/physrevb.97.024424

Cited by 6 publications

(4 citation statements)

References 55 publications

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“…5(b). The oscillation frequency decreases with the increasing of current density, similar to the situation of regular spin-valve based oscillator [35], although the former has a slightly higher frequency owing to the additional exchange field in SAF. Similar change of blue shift to red shift of oscillation frequency dependence on current density due to applied field is reported in the studies based on LLG equation [22,40].…”

Section: Simulation and Discussionsupporting

confidence: 56%

“…Different from regular spin-valve based oscillator [35], the oscillation frequency of F1 in spin-valve-based SAF oscillator increases with the increase in current density in a distinct nonlinear manner, described as follow. In the relatively broad and weak current density region, the frequency increasing is mild, while in the other relatively narrow and strong current density region, the frequency increasing is acute, and the stronger the current density is, the more acute the frequency increase becomes.…”

Section: Simulation and Discussionmentioning

confidence: 99%

“…For more information about the contribution of short-wavelength magnon excitation to magnetic relaxation, please refer to Ref. [35]. Bloch-Bloembergen-Slonczewski (BBS) equation has been established to study magnetic precession in regular STT oscillator with a single magnetic layer acting as the free magnetic layer [35], which demonstrated that T 2 > T 1 is crucial for stable STT oscillation.…”

Section: Theoretical Modelmentioning

confidence: 99%

See 2 more Smart Citations

Terahertz spin-transfer torque oscillator based on a synthetic antiferromagnet

Zhong

Qiao

Shen

et al. 2020

Journal of Magnetism and Magnetic Materials

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Bloch-Bloembergen-Slonczewski equation is adopted to simulate magnetization dynamics in spin-valve based spin-transfer torque oscillator with synthetic antiferromagnet acting as a free magnetic layer. High frequency up to the terahertz scale is predicted in synthetic antiferromagnet spin-transfer torque oscillator with no external magnetic field if the following requirements are fulfilled: antiferromagnetic coupling between synthetic antiferromagnetic layers is sufficiently strong, and the thickness of top (bottom) layer of synthetic antiferromagnet is sufficiently thick (thin) to achieve a wide current density window for the high oscillation frequency. Additionally, the transverse relaxation time of the free magnetic layer should be sufficiently larger compared with the longitudinal relaxation time. Otherwise, stable oscillation cannot be sustained or scenarios similar to regular spin valve-based spin-transfer torque oscillator with relatively low frequency will occur. Our calculations pave a new way for exploring THz spintronics devices.

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Section: Simulation and Discussionsupporting

confidence: 56%

Section: Simulation and Discussionmentioning

confidence: 99%

Section: Theoretical Modelmentioning

confidence: 99%

See 1 more Smart Citation

Terahertz spin-transfer torque oscillator based on a synthetic antiferromagnet

Zhong

Qiao

Shen

et al. 2020

Journal of Magnetism and Magnetic Materials

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“…The total angular momentum deposited per unit time into the slab is equal to the total spin current multiplied by (refs 4 , 34 ). Despite spin scattering mechanisms could transfer part of the angular momentum to the lattice, the generation of spin-torque by magnons is a well-documented phenomenon 35 – 39 . Therefore the injection of paramagnons into the FM material is expected to significantly contribute to the STT when the system is kept close to the NM Curie temperature.…”

Section: Discussionmentioning

confidence: 99%

Paramagnon-Enhanced Spin Currents in a Lattice near the Curie Point

Finazzi

Bottegoni

Zucchetti

et al. 2018

Sci Rep

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Spin transport phenomena have been shown to be highly enhanced when the temperature approaches the Curie point of the material sustaining a spin flow. Here we propose a simple - yet unifying - explanation for such enhancements, based on a random-phase model accounting for the spin fluctuations within a ferromagnetic material in the paramagnetic phase. We show that pure spin currents carried by conduction electrons injected into a paramagnetic lattice of mutually interacting localized magnetic moments can be enhanced close to the Curie temperature by the exchange interaction between the lattice sites and the non vanishing spin density associated with the spin current. The latter partially aligns the magnetic moments of the lattice, generating a flow of paramagnons that contribute to the total spin current, resulting in an enhancement that can be as large as tenfold.

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Spin–transfer torque oscillator in magnetic tunneling junction with short–wavelength magnon excitation

et al. 2018

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Bloch–Bloembergen–Slonczewski (BBS) equation is established by extending Bloch–Bloembergen equation, and it is used to study magnetization oscillation in the free magnetic layer of a magnetic tunneling junction. Since both short–wavelength magnon excitation and spin–transfer torque are taken into account in the BBS equation, it is distinguished from Landau–Lifshitz–Gilbert–Slonczewski equation. The macro–spin BBS model predicts that the transverse relaxation time in free magnetic layer should be long enough, as compared with the longitudinal relaxation time, to achieve stable magnetization oscillation for spin–transfer torque oscillator application. Moreover, field–like torque favors the tolerance of fast transverse relaxation, which makes magnetic tunneling junction a better choice than spin valve for the spin–transfer torque oscillator application.

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Magnetization precession by short-wavelength magnon excitations and spin-transfer torque

Cited by 6 publications

References 55 publications

Terahertz spin-transfer torque oscillator based on a synthetic antiferromagnet

Terahertz spin-transfer torque oscillator based on a synthetic antiferromagnet

Paramagnon-Enhanced Spin Currents in a Lattice near the Curie Point

Spin–transfer torque oscillator in magnetic tunneling junction with short–wavelength magnon excitation

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