Charge pumping and the colored thermal voltage noise in spin valves

We measure the low-frequency thermal fluctuations of pure spin current in a platinum film deposited on yttrium iron garnet via the inverse spin Hall effect (ISHE)-mediated voltage noise as a function of the angle α between the magnetization and the transport direction. The results are consistent with the fluctuation-dissipation theorem in terms of the recently discovered spin Hall magnetoresistance (SMR). We present a microscopic description of the α dependence of the voltage noise in terms of spin-current fluctuations and ISHE.

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“…(14) is simply multiplied by cos 2 α [33], because only the z projection (cos α) of the fluctuating ISHE current [Eq. (10) …”

Section: Theorymentioning

confidence: 99%

Spin Hall noise

et al. 2014

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“…However, frequency-dependent, i.e., colored noise can contain interesting information on the system at hand. For example, in a recent paper Xiao et al [4] show that, via the mechanism of spin pumping [5], a thermally agitated spin valve emits noisy currents with a colored power spectrum. They show that the peaks in the spectrum coincide with the precession frequency of the free ferromagnet of the spin valve.…”

Section: Introductionmentioning

confidence: 99%

Spin motive forces and current fluctuations due to Brownian motion of domain walls

Lucassen

Duine

2010

Solid State Communications

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We compute the power spectrum of the noise in the current due to spin motive forces by a fluctuating domain wall. We find that the power spectrum of the noise in the current is colored, and depends on the Gilbert damping, the spin transfer torque parameter β, and the domain-wall pinning potential and magnetic anisotropy. We also determine the average current induced by the thermally-assisted motion of a domain wall that is driven by an external magnetic field. Our results suggest that measuring the power spectrum of the noise in the current in the presence of a domain wall may provide a new method for characterizing the current-to-domain-wall coupling in the system.

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“…8 It has been shown that the noise in magnetic structures, such as spin valves, can be colored, i.e., it can have a nontrivial frequency dependence. 9 In diffusive metallic conductors colored noise has been observed experimentally, 10 however in magnetic structures it still requires further investigation.…”

Section: Introductionmentioning

confidence: 99%

ac- and dc-driven noise andI−Vcharacteristics of magnetic nanostructures

Tretiakov

Mitra

2010

Phys. Rev. B

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We study a structure consisting of a ferromagnetic ͑F͒ layer coupled to two normal metal ͑N͒ leads. The system is driven out of equilibrium by the simultaneous application of external dc and ac voltages across the N/F/N structure. Using the Keldysh diagrammatic approach, and modeling the ferromagnet as a classical spin of size S ӷ 1, we derive the Langevin equation for the magnetization dynamics and calculate the noise correlator. We find that the noise has an explicit frequency dependence in addition to depending on the characteristics of the ac and dc drive. Further, we calculate the current-voltage characteristics of the structure to O͑1 / S 2 ͒ and find that the nonequilibrium dynamics of the ferromagnetic layer gives rise to corrections to the current that are both linear and nonlinear in voltage.

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Charge pumping and the colored thermal voltage noise in spin valves

Cited by 18 publications

References 54 publications

Spin Hall noise

Spin Hall noise

Spin motive forces and current fluctuations due to Brownian motion of domain walls

ac- and dc-driven noise andI−Vcharacteristics of magnetic nanostructures

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