Magnetic-field tailoring of the terahertz polarization emitted from a spintronic source

Hibberd, M. T.; Lake, D. S.; Johansson, N. A. B.; Thomson, Thomas; Jamison, S. P.; Graham, D. M.

doi:10.1063/1.5055736

Cited by 67 publications

(42 citation statements)

References 28 publications

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“…In the center of the beam focus, the measured transverse THz-field component exhibited a node (Figure 21c) whereas its longitudinal component featured a maximum. A longitudinal field with a peak strength of approximately 18 kV cm −1 was generated [114] (Figure 21d), thus demonstrating the potential of STEs for spatiotemporally tailored THz fields.…”

Section: Large-area Spintronic Thz Emittersmentioning

confidence: 84%

“…To demonstrate the last feature, Hibberd et al [114] recently applied a patterned external magnetic field to a large-area STE (Figure 21a) to generate a quadrupole-like THz beam profile (Figure 21b). In the center of the beam focus, the measured transverse THz-field component exhibited a node (Figure 21c) whereas its longitudinal component featured a maximum.…”

Section: Large-area Spintronic Thz Emittersmentioning

confidence: 99%

See 1 more Smart Citation

Laser‐Driven Strong‐Field Terahertz Sources

Fülöp

Tzortzakis

Kampfrath

2019

Advanced Optical Materials

284

147

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reason for this interest relies on the fact that THz radiation can couple resonantly to numerous fundamental motions of ions, electrons, and electron spins in all phases of matter. For example, in solids, the THz range overlaps with the frequency of lattice vibrations (phonons), the collision rates of conduction electrons, the binding energy of bound electron-hole pairs (excitons), and the precession frequency of spin waves (magnons). Consequently, THz radiation, both continuous-wave and pulsed, has been used for characterization of and gaining insight into elementary processes in complex materials. The majority of these studies used relatively weak THz fields and, thus, probed the linear response of the material, without inducing notable material modifications.Only recently, however, completely new avenues in THz science were opened up by triggering nonlinear THz responses of materials. [3][4][5][6][7][8][9][10][11][12][13] Instead of using weak fields to primarily observe selected THz modes such as phonons or magnons, strong fields allow one to actively drive them to unprecedentedly large amplitudes, potentially thereby resulting in novel states of matter. [6,8,11] For example, simulations suggest that exciting matter with intense THz transients may lead to massive modifications of electrically [14] or magnetically [15] ordered domains and enable the acceleration of free ions to ≈1 MeV, [16] and postacceleration to 50-100 MeV energies. [17] Remarkable experimental results such as switching of magnetic order, [18,19] parametric amplification of optical phonons, [20] novel insights into spin-lattice coupling, [21,22] and acceleration of free electrons in a THz linear accelerator [23] were achieved only recently. This progress has been made possible by the development of laser-driven table-top THz sources routinely providing pulses with unprecedented energies and peak electric and magnetic field strengths throughout the entire THz spectral range. Different laser-based THz pulse generation techniques can be used to access different parts of the spectral range extending from 0.1 to 10 THz. Some of the recently developed technologies enable the generation of radiation with even larger bandwidth or tuning range up to 100 THz and beyond, which lead to an extension of what is called the THz spectral range. An overview of the approximate spectral coverage and the achieved highest pulse energies and peak electric-field strengths of various laserdriven technologies is given in Figure 1. ScopeIn this work, the basic principles of femtosecond-laser-driven intense pulsed THz sources and their recent development are reviewed. These sources are capable of delivering peak electric field strengths on the MV cm −1 scale. Corresponding typical THz pulse energies are on the µJ-to-mJ level, depending on A review on the recent development of intense laser-driven terahertz (THz) sources is provided here. The technologies discussed include various types of sources based on optical rectification (OR), spintronic emitters, and laserfilame...

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Section: Large-area Spintronic Thz Emittersmentioning

confidence: 84%

Section: Large-area Spintronic Thz Emittersmentioning

confidence: 99%

Laser‐Driven Strong‐Field Terahertz Sources

Fülöp

Tzortzakis

Kampfrath

2019

Advanced Optical Materials

284

147

View full text Add to dashboard Cite

show abstract

“…For circularly polarized optical pulse used for excitation, the THz emitted pulse is linearly polarized, with polarization plane being helicity dependent. Polarization control of THz wave by spatially varying magnetic field (quadrupole-like in a demonstrator 18 ) was suggested in Ref. 16 .…”

Section: Introductionmentioning

confidence: 99%

Polarization control of THz emission using spin-reorientation transition in spintronic heterostructure

Khusyainov

Ovcharenko

Gaponov

et al. 2021

Sci Rep

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Polarization of electromagnetic waves plays an extremely important role in interaction of radiation with matter. In particular, interaction of polarized waves with ordered matter strongly depends on orientation and symmetry of vibrations of chemical bonds in crystals. In quantum technologies, the polarization of photons is considered as a “degree of freedom”, which is one of the main parameters that ensure efficient quantum computing. However, even for visible light, polarization control is in most cases separated from light emission. In this paper, we report on a new type of polarization control, implemented directly in a spintronic terahertz emitter. The principle of control, realized by a weak magnetic field at room temperature, is based on a spin-reorientation transition (SRT) in an intermetallic heterostructure TbCo2/FeCo with uniaxial in-plane magnetic anisotropy. SRT is implemented under magnetic field of variable strength but of a fixed direction, orthogonal to the easy magnetization axis. Variation of the magnetic field strength in the angular (canted) phase of the SRT causes magnetization rotation without changing its magnitude. The charge current excited by the spin-to-charge conversion is orthogonal to the magnetization. As a result, THz polarization rotates synchronously with magnetization when magnetic field strength changes. Importantly, the radiation intensity does not change in this case. Control of polarization by SRT is applicable regardless of the spintronic mechanism of the THz emission, provided that the polarization direction is determined by the magnetic moment orientation. The results obtained open the prospect for the development of the SRT approach for THz emission control.

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“…Maximum signal was observed for 3 repetitions of Fe/Pt/MgO layers while above 3 the detected THz signal dropped, due to the absorption of light. Hibberd et al [44] followed another route to manipulate the THz radiation. They altered not the layer stack but the magnetic field pattern that is applied to the spintronic source.…”

Section: Stack Geometry Dependencementioning

confidence: 99%

THz spintronic emitters: a review on achievements and future challenges

2020

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The field of THz spintronics is a novel direction in the research field of nanomagnetism and spintronics that combines magnetism with optical physics and ultrafast photonics. The experimental scheme of the field involves the use of femtosecond laser pulses to trigger ultrafast spin and charge dynamics in thin films composed of ferromagnetic and nonmagnetic thin layers, where the nonmagnetic layer features a strong spin–orbit coupling. The technological and scientific key challenges of THz spintronic emitters are to increase their intensity and to shape the frequency bandwidth. To achieve the control of the source of the radiation, namely the transport of the ultrafast spin current is required. In this review, we address the generation, detection, efficiency and the future perspectives of THz emitters. We present the state-of-the-art of efficient emission in terms of materials, geometrical stack, interface quality and patterning. The impressive so far results hold the promise for new generation of THz physics based on spintronic emitters.

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Magnetic-field tailoring of the terahertz polarization emitted from a spintronic source

Cited by 67 publications

References 28 publications

Laser‐Driven Strong‐Field Terahertz Sources

Laser‐Driven Strong‐Field Terahertz Sources

Polarization control of THz emission using spin-reorientation transition in spintronic heterostructure

THz spintronic emitters: a review on achievements and future challenges

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