Power dependence of pure spin current injection by quantum interference

Ruzicka, Brian A.; Zhao, Hui

doi:10.1103/physrevb.79.155204

Cited by 6 publications

(6 citation statements)

References 46 publications

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“…6), as predicted by a model based on Fermi's golden rule [57,127]. As a consequence, the density of the injected pure spin current increases monotonically with the excitation intensities [64].…”

Section: E Efficiency Of the Quantum Interference To Inject Pure Spimentioning

confidence: 59%

“…We find that P LO 4 nW. The optical power corresponding to ΔI, ΔP, is measured by modulating the injected current density, which is achieved by modulating Δϕ with the electro-optic phase modulator [64]. We found that under our experimental conditions, the maximum value of ΔP is below 0.1 nW.…”

Section: A Second-harmonic Generation Induced By Pure Spin Currentsmentioning

confidence: 65%

“…To investigate this issue, we studied the current injection efficiency as a function of the relative strength of the two transition pathways driven by the two laser pulses [64]. This is done by measuring the spin transport length as we vary the carrier density injected by each individual pulse, but we keep the total density unchanged.…”

Section: E Efficiency Of the Quantum Interference To Inject Pure Spimentioning

confidence: 99%

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Optical studies of ballistic currents in semiconductors [Invited]

Ruzicka

Zhao

2012

J. Opt. Soc. Am. B

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We present a summary of recent studies of ballistic currents using nonlinear optical techniques. Quantum interference between one-and two-photon absorption pathways is used to inject and control ballistic currents in GaAs samples. With this, a pure charge current, pure spin current, or spin-polarized charge current can be injected by changing the polarization configuration of the two pump pulses. Such currents are temporally and spatially resolved using high-resolution pump-probe techniques, including a derivative-detection scheme, which allows detection of the motion of carriers as small as 0.1 nm. Observation of the intrinsic inverse spin Hall effect in the ballistic regime, a study of time-resolved ballistic spin-polarized charge currents, and a study of the efficiency of spin current injection by quantum interference were all achieved using these techniques. Additionally, we discuss demonstrations of second-order nonlinear optical effects induced by charge and spin currents, which allow for the nondestructive, noninvasive, and real-time imaging of currents.

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Section: E Efficiency Of the Quantum Interference To Inject Pure Spimentioning

confidence: 59%

Section: A Second-harmonic Generation Induced By Pure Spin Currentsmentioning

confidence: 65%

Section: E Efficiency Of the Quantum Interference To Inject Pure Spimentioning

confidence: 99%

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Optical studies of ballistic currents in semiconductors [Invited]

Ruzicka

Zhao

2012

J. Opt. Soc. Am. B

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“…8,9 However, for the conceptually similar injection of pure spin currents where dielectric relaxation does not occur, even a detailed experimental analysis did not reveal departures from the established χ (3) picture. 10 Theoretical results, instead, suggest that strong irradiance with either ω or 2ω pulses should reveal marked departures from the perturbative χ (3) scaling. [11][12][13] Those deviations are related to macroscopic state filling during the interaction with femtosecond light pulses.…”

Section: Introductionmentioning

confidence: 98%

Femtosecond quantum interference control of electrical currents in GaAs: Signatures beyond the perturbativeχ(3)limit

et al. 2013

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We present a comprehensive experimental and theoretical study of the power dependence of coherently controlled currents in bulk GaAs. Currents are optically induced by phase-stable femtosecond ω/2ω pulse pairs. For moderate irradiances, these currents are linked to the third-order optical nonlinearity χ (3) (0; ω,ω,−2ω).Here we focus on elevated irradiances where absorption saturation and ultimately the onset of Rabi oscillations contribute to the optical response. Current diagnostics is achieved electrically by recording the photoresponse of contacted specimens of low temperature grown GaAs as a function of the relative phase of the ω and 2ω pulses. For stronger ω irradiance we find the magnitude of the coherently controlled current to be markedly reduced when compared to the χ (3) expectation dJ /dt ∝ E 2 ω E 2ω . Additional pump-probe type experiments corroborate that this current saturation is indeed predominantly linked to macroscopic band filling. Theoretical simulations for the coherently controlled current based on a 14 band k · p model agree well with the experimental trends.

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“…We find that P LO = 4 nW. The optical power corresponding to ∆I, ∆P , is measured by modulating the average velocity of each spin system, and therefore the current density, with an electro-optic phase modulator 22 (see Supplementary Information for details). Under our experimental conditions, the maximum value of ∆P is about 200 times lower than P LO (see Fig.…”

mentioning

confidence: 99%

Observation of second-harmonic generation induced by pure spin currents

Werake

Zhao

2010

Nature Phys

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Extensive efforts are currently being devoted to developing a new electronic technology, called spintronics, where the spin of electrons is explored to carry information. [1,2] Several techniques have been developed to generate pure spin currents in many materials and structures. [3-10] However, there is still no method available that can be used to directly detect pure spin currents, which carry no net charge current and no net magnetization. Currently, studies of pure spin currents rely on measuring the induced spin accumulation with optical techniques [5, 11-13] or spin-valve configurations. [14-17] However, the spin accumulation does not directly reflect the spatial distribution or temporal dynamics of the pure spin current, and therefore cannot monitor the pure spin current in a real-time and real-space fashion. This imposes severe constraints on research in this field. Here we demonstrate a second-order nonlinear optical effect of the pure spin current. We show that such a nonlinear optical effect, which has never been explored before, can be used for the non-invasive, non-destructive, and real-time imaging of pure spin currents. Since this detection scheme does not rely on optical resonances, it can be generally applied in a wide range of materials with different electronic bandstructures. Furthermore, the control of nonlinear optical properties of materials with pure spin currents may have potential applications in photonics integrated with spintronics.Comment: 19 pages, 3 figures, supplementary discussion adde

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Power dependence of pure spin current injection by quantum interference

Cited by 6 publications

References 46 publications

Optical studies of ballistic currents in semiconductors [Invited]

Optical studies of ballistic currents in semiconductors [Invited]

Femtosecond quantum interference control of electrical currents in GaAs: Signatures beyond the perturbativeχ(3)limit

Observation of second-harmonic generation induced by pure spin currents

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