Efficient sorting of free electron orbital angular momentum

McMorran, Benjamin; Harvey, Tyler R.; Lavery, Martin P. J.

doi:10.1088/1367-2630/aa5f6f

Cited by 40 publications

(36 citation statements)

References 30 publications

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“…Only recently the first demonstration of this method has been realised using holographic gratings (with all the ensuing limitations in terms of efficiency) [225]. There were also proposals to employ more efficient electrostatic optical components, but these have yet to be realised experimentally [226]. Several other approaches to OAM measurement have been developed in optics, with sensitivity up to the single-photon level [34,227].…”

Section: Advantagesmentioning

confidence: 99%

“…14 Thus, retrieving the desired magnetic information about the sample requires an efficient far-field OAM sorter for transmitted electrons. Such an ideal sorter is not currently available (as discussed in Section 3.3), although promising setups have been proposed [226]. The first hints of this effect have been demonstrated on a ferromagnetic iron sample, using a forked holographic grating as an OAM filter before the electron spectrometer [77].…”

Section: Eels Cross-sections and Selection Rules Magnetic Dichroismmentioning

confidence: 99%

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Theory and applications of free-electron vortex states

Bliokh¹,

Иванов²,

Guzzinati³

et al. 2017

Physics Reports

288

347

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Both classical and quantum waves can form vortices: with helical phase fronts and azimuthal current densities. These features determine the intrinsic orbital angular momentum carried by localized vortex states. In the past 25 years, optical vortex beams have become an inherent part of modern optics, with many remarkable achievements and applications. In the past decade, it has been realized and demonstrated that such vortex beams or wavepackets can also appear in free electron waves, in particular, in electron microscopy. Interest in free-electron vortex states quickly spread over different areas of physics: from basic aspects of quantum mechanics, via applications for fine probing of matter (including individual atoms), to high-energy particle collision and radiation processes. Here we provide a comprehensive review of theoretical and experimental studies in this emerging field of research. We describe the main properties of electron vortex states, experimental achievements and possible applications within transmission electron microscopy, as well as the possible role of vortex electrons in relativistic and high-energy processes. We aim to provide a balanced description including a pedagogical introduction, solid theoretical basis, and a wide range of practical details. Special attention is paid to translate theoretical insights into suggestions for future experiments, in electron microscopy and beyond, in any situation where free electrons occur.

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Section: Advantagesmentioning

confidence: 99%

Section: Eels Cross-sections and Selection Rules Magnetic Dichroismmentioning

confidence: 99%

Theory and applications of free-electron vortex states

Bliokh¹,

Иванов²,

Guzzinati³

et al. 2017

Physics Reports

288

347

View full text Add to dashboard Cite

show abstract

“…What we expect to observe in practice is (12) where is the product of two Gaussian functions describing broadening introduced by the experimental setup. The OAM is treated as a continuous variable, since the sorter can transform a vortex with topological charge l in a spot centered at coordinate Cl [19,20,21] with a lateral extension equal to (where C is a constant that depends on the sorter parameters and is assigned a value of unity for simplicity in the images presented in the main text). Figure 3b shows the result of this convolution procedure for and , as this is the resolution expected using a sorter in a fan-out configuration, as recently demonstrated for optical sorters [35].…”

Section: Resultsmentioning

confidence: 99%

Orbital angular momentum resolved electron magnetic chiral dichroism

et al. 2019

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We propose a highly efficient atomically-resolved mode of electron magnetic chiral dichroism. This method exploits the recently introduced orbital angular momentum spectrometer to analyze the inelastically scattered electrons allowing for simultaneous dispersion in both energy and angular momentum. The technique offers several advantages over previous formulations of electron magnetic chiral dichroism as it requires much simpler experimental conditions in terms of specimen orientation and thickness. A novel simulation algorithm, based on the multislice description of the beam propagation, is used to anticipate the advantages of the new approach over current electron magnetic chiral dichroism implementations. Numerical calculations confirm an increased magnetic signal to noise ratio with in plane atomic resolution.

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“…We have realized an electrostatic "sorter" for electrons, which can be used to analyze the components of orbital angular momentum (OAM) of an electron beam [1]. It is based on the use of a combination of microscope lenses and additional customized phase elements that are positioned in the back focal plane of the objective and the first intermediate image planes (SAD aperture) of the microscope.…”

mentioning

confidence: 99%