Current-driven ferromagnetic resonance, mechanical torques, and rotary motion in magnetic nanostructures

Kovalev, Alexey A.; Bauer, G.; Brataas, Arne

doi:10.1103/physrevb.75.014430

Cited by 78 publications

(81 citation statements)

References 41 publications

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“…When it is included, the symmetric dip in the power spectrum in Fig. 2 is skewed by g i similar to for the spin diode effect discussed by Kupferschmidt et al 48 and Kovalev et al 32 For asymmetric spin valves, a nonmonotonic angular dependence of the magnetoresistance and a vanishing torkance at a noncollinear magnetization configuration has been demonstrated. [49][50][51][52][53] A sign change in torkance leads to a sign change in the charge pumping voltage.…”

Section: Discussionmentioning

confidence: 78%

“…In that regime, the resistances of the bulk ferromagnet over the spin-flip diffusion length are in series with the interface resistances, whereas the remoter parts of the ferromagnets are magnetically inert series resistances. The regime in which the layers become thinner than the spin-flip diffusion length was treated by Kovalev et al 32 In this and Sec. III, we focus on the spin-active region in the spin valve, which includes the NM spacer and small part ͑of the order of the spin-flip diffusion length͒ of the FM layers as indicated by the dashed box in Fig.…”

Section: Introductionmentioning

confidence: 99%

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Charge pumping and the colored thermal voltage noise in spin valves

et al. 2009

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Spin pumping by a moving magnetization gives rise to an electric voltage over a spin valve. Thermal fluctuations of the magnetization manifest themselves as increased thermal voltage noise with absorption lines at the ferromagnetic resonance frequency and/or zero frequency. The effect depends on the magnetization configuration and can be of the same order of magnitude as the Johnson-Nyquist thermal noise. Measuring colored voltage noise is an alternative to ferromagnetic resonance experiments for nanoscale ferromagnetic circuits.

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Section: Discussionmentioning

confidence: 78%

Section: Introductionmentioning

confidence: 99%

Charge pumping and the colored thermal voltage noise in spin valves

et al. 2009

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“…In a nanowire with an only FM/NM interface the FM layer servers as a polarizer for an electric current, and spin flip processes at the FM/NM interface produce a mechanical torque in the sample [16][17][18][19] . Another modification of NEMMS (see [20][21][22] ) is analogous to spin-valves and includes at least two FM layers -one is a polarizer and the magnetization of the other is rotated by STT. Oscillations of magnetization, in turn, induce the mechanical movement, due to the presence of spin-lattice coupling.…”

Section: Introductionmentioning

confidence: 99%

Magnetoelastic coupling and possibility of spintronic electromagnetomechanical effects

Gomonay

Kondovych

Локтев

2012

Low Temperature Physics

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Nanoelectromangetomechanical systems (NEMMS) open up a new path for the development of high speed autonomous nanoresonators and signal generators that could be used as actuators, for information processing, as elements of quantum computers etc. Those NEMMS that include ferromagnetic layers could be controlled by the electric current due to effects related with spin transfer. In the present paper we discuss another situation when the current-controlled behaviour of nanorod that includes an antiferro-(instead of one of ferro-) magnetic layer. We argue that in this case ac spin-polarized current can also induce resonant coupled magneto-mechanical oscillations and produce an oscillating magnetization of antiferromagnetic (AFM) layer. These effects are caused by i ) spin-transfer torque exerted to AFM at the interface with nonmagnetic spacer and by ii ) the effective magnetic field produced by the spin-polarized free electrons due to sd-exchange.The described nanorod with an AFM layer can find an application in magnetometry and as a current-controlled high-frequency mechanical oscillator.

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“…This solution is consistent with prior results that have measured the interfacial spin accumulation as a function of thickness by its action on an adjacent ferromagnetic layer. The flow of spins within the material is equivalent to a flow of angular momentum [42]. Because total angular momentum is conserved, the change in angular momentum of the electrons must be compensated by a change in angular momentum of the lattice.…”

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confidence: 99%

Nanomechanical detection of the spin Hall effect

2016

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The spin Hall effect creates a spin current in response to a charge current in a material that has strong spin-orbit coupling. The size of the spin Hall effect in many materials is disputed, requiring independent measurements of the effect. We develop a novel mechanical method to measure the size of the spin Hall effect, relying on the equivalence between spin and angular momentum. The spin current carries angular momentum, so the flow of angular momentum will result in a mechanical torque on the material. We determine the size and geometry of this torque and demonstrate that it can be measured using a nanomechanical device. Our results show that measurement of the spin Hall effect in this manner is possible and also opens possibilities for actuating nanomechanical systems with spin currents.The spin Hall effect [1,2], which is the generation of a spin current in a material due to an applied charge current in the presence of strong spin-orbit coupling, has been proposed as a novel method of spin manipulation for spintronics applications. Spin currents generated by the spin Hall effect have been used to excite high-and lowfrequency magnetic dynamics in nanostructures [3][4][5][6][7][8][9][10][11], and may become useful for future low-power spintronic logic and storage devices [12]. The spin Hall effect has been observed in a variety of materials with strong spin orbit coupling, including semiconductors such as Si and GaAs [13][14][15][16]; graphene with adsorbed impurities [17]; heavy metals with strong spin-orbit coupling such as Pt, Ta and W [4,11,[18][19][20]; and metals doped with large spin-orbit-coupled impurities [21][22][23]. However, quantification of the SHE through fundamental parameters remains a challenge.The figure-of-merit for SHE materials is the spin Hall angle, Θ SH , which is often stated as the proportionality between the magnitude of generated spin current and the magnitude of input charge current, |J s | = h 2e Θ SH J c [24,25], where J s is the component of the spin current perpendicular to the charge current and J c is the charge current. Measurements and characterization of Θ SH have, as yet, been limited to methods based on optical, electrical, and magnetic effects, which require knowledge of Kerr rotation coupling, metallic interfaces, magnetic properties, and spin diffusion parameters to quantify Θ SH accurately [15,26]. As such, reported values of Θ SH span orders of magnitude for materials such as Pt and Pd [19,[27][28][29][30][31][32][33][34][35]. Open questions such as the dependence of Θ SH on growth conditions, film thickness, impurity level, frequency, and other systematic parameters must be addressed both experimentally and theoretically. Since the inverse SHE is used to measure spin transport due to the spin Seebeck effect and spin pumping, accurate knowledge of the spin Hall angle is important for metrology. One intriguing new result implies that the spin Hall angle is complex-valued, resulting in a phase shift between an applied AC charge current and the resulting AC spin cu...

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Current-driven ferromagnetic resonance, mechanical torques, and rotary motion in magnetic nanostructures

Cited by 78 publications

References 41 publications

Charge pumping and the colored thermal voltage noise in spin valves

Charge pumping and the colored thermal voltage noise in spin valves

Magnetoelastic coupling and possibility of spintronic electromagnetomechanical effects

Nanomechanical detection of the spin Hall effect

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