Nanoscale magnetic imaging using circularly polarized high-harmonic radiation

Kfir, Ofer; Zayko, Sergey; Nolte, Christina; Sivis, Murat; Möller, Marcel; Hebler, Birgit; Arekapudi, Sri Sai Phani Kanth; Steil, Daniel; Schäfer, Sascha; Albrecht, Manfred; Cohen, Oren; Mathias, Stefan; Ropers, Claus

doi:10.1126/sciadv.aao4641

Cited by 105 publications

(61 citation statements)

References 56 publications

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“…Observing these magnetic phenomena on their intrinsic length and time scales requires experimental tools capable of simultaneous nanometer spatial and nanosecond to femtosecond temporal resolution. Whereas photoelectron [19] and magneto-optical schemes using pulsed radiation sources from the visible [20] to the x-ray [21][22][23] regime inherently offer high temporal resolution, the particular advantages of electron beam techniques have yet to be fully exploited in the ultrafast domain.…”

Section: Introductionmentioning

confidence: 99%

Few-nm tracking of current-driven magnetic vortex orbits using ultrafast Lorentz microscopy

et al. 2020

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Transmission electron microscopy is one of the most powerful techniques to characterize nanoscale magnetic structures. In light of the importance of fast control schemes of magnetic states, time-resolved microscopy techniques are highly sought after in fundamental and applied research. Here, we implement time-resolved Lorentz imaging in combination with synchronous radio-frequency excitation using an ultrafast transmission electron microscope. As a model system, we examine the current-driven gyration of a vortex core in a 2 µm-sized magnetic nanoisland. We record the trajectory of the vortex core for continuous-wave excitation, achieving a localization precision of ±2 nm with few-minute integration times. Furthermore, by tracking the core position after rapidly switching off the current, we find a temporal hardening of the free oscillation frequency and an increasing orbital decay rate attributed to local disorder in the vortex potential. arXiv:1907.04608v1 [cond-mat.mes-hall]

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Section: Introductionmentioning

confidence: 99%

Few-nm tracking of current-driven magnetic vortex orbits using ultrafast Lorentz microscopy

et al. 2020

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“…Elastic and inelastic scattering times were identified in dielectric nanoparticles [15]. Dynamics of magnetization could be probed [16]. .…”

Section: Introductionmentioning

confidence: 99%

High-order harmonic generation in an active grating

et al. 2019

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We study theoretically and experimentally High Harmonic Generation (HHG) using two non collinear driving fields focused in gases. We show that these two fields form a non stationary blazed active grating in the generation medium. The intensity and phase structure of this grating rule the far field properties of the emission, such as the relative amplitude of the diffraction orders. Full macroscopic calculations and experiments support this general analysis. This insight into the HHG process allows us to envision new structuration schemes to convert femtosecond lasers to attosecond pulses with increased efficiency.

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“…Moreover, means for controlling the polarization of the emitted coherent radiation have been proposed and/or experimentally demonstrated [64,88,89,94,95,97,[99][100][101][102][103][104][105][106][107][108][109][110]. There exist many important applications of isolated short laser pulses in the extreme ultraviolet and x-ray regimes with controlled polarization for studying chiral-sensitive light-matter interactions in, e.g., magnetic materials [88,97,100,[111][112][113] or polyatomic molecules [58,96,101,108,114].…”

Section: Introductionmentioning

confidence: 99%

Analytic description of high-order harmonic generation in the adiabatic limit with application to an initial s state in an intense bicircular laser pulse

et al. 2019

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An analytic description of high-order harmonic generation (HHG) is proposed in the adiabatic (low-frequency) limit for an initial s state and a laser field having an arbitrary wave form. The approach is based on the two-state time-dependent effective range theory and is extended to the case of neutral atoms and positively charged ions by introducing ad hoc the Coulomb corrections for HHG. The resulting closed analytical form for the HHG amplitude is discussed in terms of real classical trajectories. The accuracy of the results of our analytic model is demonstrated by comparison with numerical solutions of the time-dependent Schrödinger equation for a strong bicircular field composed of two equally intense components with carrier frequencies ω and 2ω and opposite helicities. In particular, we demonstrate the effect of ionization gating on HHG in a bicircular field, both for the case that the two field components are quasimonochromatic and for the case that the field components are time-delayed short pulses. We show how ionization in a strong laser field not only smooths the usual peak structures in HHG spectra but also changes the positions and polarization properties of the generated harmonics, seemingly violating the standard dipole selection rules. These effects appear for both short and long incident laser pulses. In the case of time-delayed short laser pulses, ionization gating provides an effective tool for control of both the HHG yield and the harmonic polarizations [Frolov et al., Phys. Rev. Lett. 120, 263203 (2018)]. For the case of short laser pulses, we introduce a simple two-dipole model that captures the physics underlying the harmonic emission process, describing both the oscillation patterns in HHG spectra and also the dependence of the harmonic polarizations on the harmonic energy.

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Nanoscale magnetic imaging using circularly polarized high-harmonic radiation

Abstract: We introduce laboratory-scale magneto-optical imaging with sub–50-nm resolution using high-harmonic radiation.

Cited by 105 publications

References 56 publications

Few-nm tracking of current-driven magnetic vortex orbits using ultrafast Lorentz microscopy

Few-nm tracking of current-driven magnetic vortex orbits using ultrafast Lorentz microscopy

High-order harmonic generation in an active grating

Analytic description of high-order harmonic generation in the adiabatic limit with application to an initial s state in an intense bicircular laser pulse

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