Current-induced effective magnetic fields in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi mathvariant="normal">Co</mml:mi><mml:mo>∕</mml:mo><mml:mi mathvariant="normal">Cu</mml:mi><mml:mo>∕</mml:mo><mml:mi mathvariant="normal">Co</mml:mi></mml:mrow></mml:math>nanopillars

Zimmler, Mariano A.; Özyilmaz, Barbaros; Chen, W.; Kent, Andrew D.; Sun, J. Z.; Rooks, M. J.; Koch, R. H.

doi:10.1103/physrevb.70.184438

Cited by 67 publications

(41 citation statements)

References 32 publications

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“…Averaging over the free layer results in xT damp y " 42 444 A/m and xT field y " 2712 A/m. These values are in good accordance with experimental findings [14]. The torques have a positive sign, i.e.…”

Section: Resultssupporting

confidence: 80%

Fieldlike and Dampinglike Spin-Transfer Torque in Magnetic Multilayers

et al. 2017

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We investigate the spin-transfer torque in a magnetic multilayer structure by means of a spin-diffusion model. The torque in the considered system, consisting of two magnetic layers separated by a conducting layer, is caused by a perpendicular-to-plane current. We compute the strength of the field-like and the damping-like torque for different material parameters and geometries. Our studies suggest that the field-like torque highly depends on the exchange coupling strength of the itinerant electrons with the magnetization both in the pinned and the free layer. While a low coupling leads to very high field-like torques, a high coupling leads to low or even negative field-like torques. The dependence of the different torque terms on system parameters is considered very important for the development of applications such as STT MRAM and spin-torque oscillators.

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Section: Resultssupporting

confidence: 80%

Fieldlike and Dampinglike Spin-Transfer Torque in Magnetic Multilayers

et al. 2017

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“…II E that a current-induced torque that acts like an effective external magnetic field can arise due to incomplete absorption of a transversely polarized spin current at the interface between the spacer and the free layer. A recent experimental report 22 has been interpreted by its authors to mean that the size of this torque-displayed in Eq. (10)-is much larger than theoretical estimates.…”

Section: Current-induced Effective Fieldsmentioning

confidence: 99%

“…Other observed dynamical behavior includes telegraph noise that is interpreted as rapid switching between two distinct states of magnetization. 16,17,18,19 Several experimental groups have used the macrospin (single domain) approximation to propose "phase diagrams" that identify the dynamical state of their spin valves as a function of J and H. 8,11,17,19,20,21,22,23 There have also been purely theoretical studies of the LLG equation (generalized to include spin-transfer torque) using both macrospin models 24,25,26,27,28,29,30 and micromagnetics simulations 31,32,33,34,35,36,37,38 that do not make the single-domain approximation. Unfortunately, it is difficult to extract a coherent picture from all this work because different authors make different choices for the physical effects they believe most affect the dynamics.…”

Section: Introductionmentioning

confidence: 99%

Macrospin models of spin transfer dynamics

2005

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The current-induced magnetization dynamics of a spin valve are studied using a macrospin (single domain) approximation and numerical solutions of a generalized Landau-Lifshitz-Gilbert equation. (2003)], we calculate the resistance and microwave power as a function of current and external field including the effects of anisotropies, damping, spin-transfer torque, thermal fluctuations, spin-pumping, and incomplete absorption of transverse spin current. While many features of experiment appear in the simulations, there are two significant discrepancies: the current dependence of the precession frequency and the presence/absence of a microwave quiet magnetic phase with a distinct magnetoresistance signature. Comparison is made with micromagnetic simulations designed to model the same experiment.

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“…Here, we only consider the first term of transverse torque and ignore the second term of smaller field-like torque since the field-like torque is very small in metallic alloys. 31,32 The scalar function g(M, P) is given by where η is the spin polarization factor, the angle between M and P is θ . M · P/M s 2 = cos θ .…”

Section: Theoretical Modelmentioning

confidence: 99%

Micromagnetic simulation of high-power spin-torque oscillator in half-metallic Heusler alloy spin valve nanopillar

Huang

Liu

et al. 2013

AIP Advances

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We investigated the spin-torque oscillator in a half-metallic Heusler alloy Co2MnSi (CMS) spin-valve nanopillar using micromagnetic simulations. Although it is known that the out-of-plane precession (OPP) usually has a larger power output than the in-plane precession (IPP), only IPP mode was experimentally observed in CMS. Our simulations revealed the fundamental and second harmonic radio frequency (rf) oscillations of the IPP mode, consistent with the experimental measurements in CMS-based pillars. Our simulations predicted that the OPP mode can be obtained under the condition of an initially antiparallel state, a small external magnetic field, and a sufficiently large current density

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Current-induced effective magnetic fields inCo∕Cu∕Conanopillars

Cited by 67 publications

References 32 publications

Fieldlike and Dampinglike Spin-Transfer Torque in Magnetic Multilayers

Fieldlike and Dampinglike Spin-Transfer Torque in Magnetic Multilayers

Macrospin models of spin transfer dynamics

Micromagnetic simulation of high-power spin-torque oscillator in half-metallic Heusler alloy spin valve nanopillar

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