Ultraintense Femtosecond Magnetic Nanoprobes Induced by Azimuthally Polarized Laser Beams

Blanco, María del Pilar; Cambronero, Ferran; Flores-Arias, M. T.; Jarque, Enrique Conejero; Plaja, Luis; Hernández-García, Carlos

doi:10.1021/acsphotonics.8b01312

Cited by 22 publications

(25 citation statements)

References 34 publications

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“…Such XUV beams with controlled angular momenta can also be used to enhance light microscopy -through high-contrast high-resolution spiralphase imaging [65] or XUV microscopy [16] -, in lithography [66], and as tailored waveforms for developing and improving spectroscopic techniques [67,68]. Finally, we note that TKAM conservation in HHG provides a new tool to study ultrafast magnetism, in particular to image magnetic domains [69], to uncover spin/charge dynamics in magnetic materials [70] and to generate ultrafast magnetic fields [71]…”

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confidence: 99%

Conservation of Torus-knot Angular Momentum in High-order Harmonic Generation

et al. 2019

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High-order harmonic generation stands as a unique nonlinear optical up-conversion process, mediated by a laser-driven electron recollision mechanism, which has been shown to conserve energy, momentum, and spin and orbital angular momentum. Here we present theoretical simulations which demonstrate that this process also conserves a mixture of the latter, the torus-knot angular momentum Jγ, by producing high-order harmonics with driving pulses that are invariant under coordinated rotations. We demonstrate that the charge Jγ of the emitted harmonics scales linearly with the harmonic order, and that this conservation law is imprinted onto the polarization distribution of the emitted spiral of attosecond pulses. We also demonstrate how the nonperturbative physics of high-order harmonic generation affect the torus-knot angular momentum of the harmonics, and we show that this configuration harnesses the spin selection rules to channel the full yield of each harmonic into a single mode of controllable orbital angular momentum.

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confidence: 99%

Conservation of Torus-knot Angular Momentum in High-order Harmonic Generation

et al. 2019

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“…First of all, we observe that the electrons’ response time delays the magnetic pulse by about 4 fs with respect to the optical pulse. We can then see that the decay of the magnetic pulse is slower than that of the optical pulse due to both the relaxation time of the electrons in gold , and the relaxation time of the energy within the structure. Finally, while the optical pulse’s peak power is the same as during the search for an optimal structure by the GA, the magnetic field B created by the antenna reaches a value of only about 1.5 T. The decay of the optical pulse stops the acceleration of the electrons before reaching their full speed.…”

Section: Resultsmentioning

confidence: 99%

Tesla-Range Femtosecond Pulses of Stationary Magnetic Field, Optically Generated at the Nanoscale in a Plasmonic Antenna

Yang

Gallas

et al. 2021

ACS Nano

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The inverse Faraday effect allows the generation of stationary magnetic fields through optical excitation only. This light−matter interaction in metals results from creating drift currents via nonlinear forces that light applies to the conduction electrons. Here, we describe the theory underlying the generation of drift currents in metals, particularly its application to photonic nanostructures using numerical simulations. We demonstrate that a gold photonic nanoantenna, optimized by a genetic algorithm, allows, under high excitation power, to maximize the drift currents and generate a pulse of stationary magnetic fields in the tesla range. This intense magnetic field, confined at the nanoscale and for a few femtoseconds, results from annular optical confinement and not from the creation of a single optical hot spot. Moreover, by controlling the incident polarization state, we demonstrate the orientation control of the created magnetic field and its reversal on demand. Finally, the stationary magnetic field's temporal behavior and the drift currents associated with it reveal the subcycle nature of this light−matter interaction. The manipulation of drift currents by a plasmonic nanostructure for the generation of stationary magnetic field pulses finds applications in the ultrafast control of magnetic domains with applications not only in data storage technologies but also in research fields such as magnetic trapping, magnetic skyrmion, magnetic circular dichroism, to spin control, spin precession, spin currents, and spin-waves, among others.

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“…Indeed, we have demonstrated that the recently developed scenario of spatially isolated femtosecond B-fields [26][27][28][29] opens the path to the ultrafast manipulation of magnetization dynamics by purely precessional effects, avoiding the heating due to the E-field or magnetization damping. Our numerical results already demonstrate that all-optical switching at the fs time scale can be achieved with circularly polarized B-fields of 275 T. However, we believe that our work paves the way towards all-optical switching at even shorter timescales, towards the attosecond regime.…”

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“…In this regard, the recent generation of spatially isolated fs magnetic fields (B-fields) opens the possibility to induce magnetization dynamics solely by the interaction with an ultrafast B-field, thus neglecting the E-field. In particular, azimuthally polarized fs laser beams have been demonstrated to induce large oscillating currents on circular apertures that, in turn, produce a Tesla-scale fs B-field, spatially isolated from the E-field [26][27][28][29]. Previously, azymuthally-polarized on-axis laser beams were used to induce mili-Tesla static B-fields [30], with applications in nanoscale magnetic excitations and photoinduced force microscopy [31,32].…”

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All-optical non-linear chiral ultrafast magnetization dynamics driven by circularly polarized magnetic fields

Sánchez-Tejerina¹,

Martín-Hernández²,

Yanes³

et al. 2022

Preprint

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Ultrafast laser pulses provide unique tools to manipulate magnetization dynamics at femtosecond timescales, where the interaction of the electric field-such as excitation of spin carriers to non-equilibrium states, generation of localized charge currents, demagnetization, or inverse Faraday effect-dominates over the magnetic field. Recent proposals using structured laser beams have enlightened the possibility to generate intense femtosecond magnetic fields, spatially isolated from the electric field. Here we demonstrate the relevance of this novel scenario to femtomagnetism, unveiling the purely precessional, non-linear, chiral response of the magnetization when subjected to circularly polarized magnetic fields. This fundamental result not only opens an avenue in the study of laser-induced ultrafast magnetization dynamics, but also sustains technological implications as a route to promote all-optical non-thermal magnetization switching both at shorter timescales-towards the attosecond regime-and at THz frequencies.

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Ultraintense Femtosecond Magnetic Nanoprobes Induced by Azimuthally Polarized Laser Beams

Cited by 22 publications

References 34 publications

Conservation of Torus-knot Angular Momentum in High-order Harmonic Generation

Conservation of Torus-knot Angular Momentum in High-order Harmonic Generation

Tesla-Range Femtosecond Pulses of Stationary Magnetic Field, Optically Generated at the Nanoscale in a Plasmonic Antenna

All-optical non-linear chiral ultrafast magnetization dynamics driven by circularly polarized magnetic fields

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