Second-Harmonic Generation Induced by Electric Currents in GaAs

Ruzicka, Brian A.; Werake, Lalani K.; Xu, Guangye; Khurgin, Jacob B.; Sherman, E. Ya.; Wu, Judy; Zhao, Hui

doi:10.1103/physrevlett.108.077403

Cited by 48 publications

(31 citation statements)

References 28 publications

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“…Previously, it has been predicted that a charge current can also induce SHG [131]. We demonstrated this effect with a similar technique and procedure [132]. By using a pair of laser pulses that are both linearly polarized alongx, a ballistic pure charge current is injected alongx, as illustrated in Fig.…”

Section: B Second-harmonic Generation Induced By Pure Charge Currentsmentioning

confidence: 80%

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: B Second-harmonic Generation Induced By Pure Charge Currentsmentioning

confidence: 80%

Optical studies of ballistic currents in semiconductors [Invited]

Ruzicka

Zhao

2012

J. Opt. Soc. Am. B

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“…One can see that d depends on the crystal length, the applied electric field, the frequency of the probe beam, and the intensity of the spin current. Set L ¼ 3 Â 10 À6 m and E 0 ¼ 3.5 Â 10 5 V m À1 , respectively, 25 we calculate the polarization rotation of the probe beam varying with J zx and x 1 . The numerical results are shown in Fig.…”

Section: Numerical Resultsmentioning

confidence: 99%

Proposed measurement of spin currents in a GaAs crystal using the electro-optical Pockels effect

Zhang

Zheng

She

2014

Journal of Applied Physics

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A new method for measuring spin currents is proposed, based on the linear electro-optic (Pockels) effect caused by the additional second-order nonlinear electric susceptibility (electro-optic tensor) generated by the spin currents. The non-zero elements of electro-optic tensor induced by spin currents in GaAs crystal are calculated, and the wave coupling theory of linear electro-optic effect is used to analyze the polarization change of a probe beam. The numerical results show that, for a linearly polarized probe beam with a frequency close to the band gap of GaAs crystal, its polarization rotation can be as large as 14 μrad under an applied electric field of about 350 V/mm. This effect should offer an alternative detection method for spintronics.

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“…[14]; see Fig Magnetoinduced second harmonic generation (mSHG) [28,29] is a promising tool for direct SC detection owing to its high temporal resolution and sensitivity to the currentdriven symmetry breaking, as demonstrated in GaAs [30,31] and multilayer graphene [32]. We performed alloptical experiments in either the front or back pump-probe scheme shown in Fig.…”

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confidence: 99%

Femtosecond Spin Current Pulses Generated by the Nonthermal Spin-Dependent Seebeck Effect and Interacting with Ferromagnets in Spin Valves

Alekhin¹,

Razdolski²,

Ilin³

et al. 2017

Phys. Rev. Lett.

104

120

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Using the sensitivity of optical second harmonic generation to currents, we demonstrate the generation of 250-fs long spin current pulses in Fe=Au=Fe=MgOð001Þ spin valves. The temporal profile of these pulses indicates ballistic transport of hot electrons across a sub-100 nm Au layer. The pulse duration is primarily determined by the thermalization time of laser-excited hot carriers in Fe. Considering the calculated spin-dependent Fe=Au interface transmittance we conclude that a nonthermal spin-dependent Seebeck effect is responsible for the generation of ultrashort spin current pulses. The demonstrated rotation of spin polarization of hot electrons upon interaction with noncollinear magnetization at Au=Fe interfaces holds high potential for future spintronic devices. DOI: 10.1103/PhysRevLett.119.017202 Optimization and control of spin currents (SC) and their interaction with magnetic constituents in heterostructures on a femtosecond time scale is key for future terahertz spintronics applications. Although electronic transport through a ferromagnet (FM), as described by Mott's two current model [1], generates a spin-polarized current, its density is intrinsically limited by Joule losses. The discovery of the spin-dependent Seebeck effect (SdSE), where thermal gradients over a bulk FM [2] or across an interface to a normal metal [3] generate SCs, opened a path towards overcoming such limitations. Indeed, shortlived thermal gradients can produce short (∼100 ps) SC pulses at densities exceeding the static Joule limit, as recently demonstrated upon laser excitation of spin-valve structures [4].Creating highly energetic electrons [5][6][7][8][9], femtosecond laser excitation is promising for SC pulse generation on subpicosecond time scales, before the electron-electron [9] and electron-lattice [8] equilibration is reached.

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Second-Harmonic Generation Induced by Electric Currents in GaAs

Cited by 48 publications

References 28 publications

Optical studies of ballistic currents in semiconductors [Invited]

Optical studies of ballistic currents in semiconductors [Invited]

Proposed measurement of spin currents in a GaAs crystal using the electro-optical Pockels effect

Femtosecond Spin Current Pulses Generated by the Nonthermal Spin-Dependent Seebeck Effect and Interacting with Ferromagnets in Spin Valves

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