Origins and demonstrations of electrons with orbital angular momentum

McMorran, Benjamin; Agrawal, Amit; Ercius, Peter; Grillo, Vincenzo; Herzing, Andrew A.; Harvey, Tyler R.; Linck, Martin; Pierce, Jordan

doi:10.1098/rsta.2015.0434

Cited by 48 publications

(32 citation statements)

References 74 publications

(136 reference statements)

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“…At the time of writing of this review, the best transmission e ciency reported by Grillo et al is 37% out of a theoretical limit of 38% for their partially blazed phase mask. On the other hand, McMorran's group (McMorran et al, 2017) reported a much larger value of 70% for the absolute transmission e ciency for their blazed mask. Clearly more work is needed to investigate the practical limits to the generation e ciencies using optimized blazed phase masks.…”

Section: Blazed Phase Maskmentioning

confidence: 99%

“…For practical reasons, the holographic di↵raction mask and the aperture masking methods are di cult to implement for atomic size vortex beams, making the astigmatism transformation method currently the most realistic method for atomic scale pure vortex beams. For e cient sorting of electron vortex beams in general, electron optical are preferred and a refractive device has recently been proposed by McMorran et al (2017).…”

Section: B Mode Conversion Analysismentioning

confidence: 99%

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Electron vortices: Beams with orbital angular momentum

et al. 2017

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The recent prediction and subsequent creation of electron vortex beams in a number of laboratories occurred after almost 20 years had elapsed since the recognition of the physical significance and potential for applications of the orbital angular momentum carried by optical vortex beams. A rapid growth in interest in electron vortex beams followed, with swift theoretical and experimental developments. Much of the rapid progress can be attributed in part to the clear similarities between electron optics and photonics arising from the functional equivalence between the Helmholtz equations governing the free space propagation of optical beams and the time-independent Schrödinger equation governing freely propagating electron vortex beams. There are, however, key di↵erences in the properties of the two kinds of vortex beams. This review is concerned primarily with the electron type, with specific emphasis on the distinguishing vortex features: notably the spin, electric charge, current and magnetic moment, the spatial distribution as well as the associated electric and magnetic fields. The physical consequences and potential applications of such properties are pointed out and analysed, including nanoparticle manipulation and the mechanisms of orbital angular momentum transfer in the electron vortex interaction with matter.

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Section: Blazed Phase Maskmentioning

confidence: 99%

Section: B Mode Conversion Analysismentioning

confidence: 99%

Electron vortices: Beams with orbital angular momentum

et al. 2017

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“…The study of orbital angular momentum has had an impact beyond the field of optics and an issue devoted to OAM would not be complete without papers looking beyond optics. We have two discussing the existence of electron vortices and their angular momentum properties [57,58].…”

Section: Recent Developments and This Theme Issuementioning

confidence: 99%

Optical orbital angular momentum

Barnett

Babiker

Padgett

2017

Phil. Trans. R. Soc. A.

117

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We present a brief introduction to the orbital angular momentum of light, the subject of our theme issue and, in particular, to the developments in the 13 years following the founding paper by Allen et al. (Allen et al. 1992 Phys. Rev. A 45 , 8185 ( doi:10.1103/PhysRevA.45.8185 )). The papers by our invited authors serve to bring the field up to date and suggest where developments may take us next. This article is part of the themed issue ‘Optical orbital angular momentum’.

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“…For example, diffraction holograms can be used in a scanning transmission electron microscope to remove aberrations [1], implement new types of interferometric phase contrast [2,3], and produce electron probes with phase vortices and quantized angular momentum [4,5].We are currently investigating the use of nanoscale gratings for off-axis STEM interferometry ( Figure 1). We have used a single grating in a scanning transmission electron microscope (STEM) to form a pathseparated electron interferometer [6].…”

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confidence: 99%

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confidence: 99%

Electron Microscopy with Structured Electrons

et al. 2017

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Nanofabricated diffractive optics are new tools for coherently dividing and manipulating electron wavefunctions, similar to how spatial light modulators are used to engineer light waves in optics. For example, diffraction holograms can be used in a scanning transmission electron microscope to remove aberrations [1], implement new types of interferometric phase contrast [2,3], and produce electron probes with phase vortices and quantized angular momentum [4,5].We are currently investigating the use of nanoscale gratings for off-axis STEM interferometry ( Figure 1). We have used a single grating in a scanning transmission electron microscope (STEM) to form a pathseparated electron interferometer [6]. In this configuration, single electrons are coherently divided before the specimen, and then focused into two or more focused probes at the specimen. We are developing ways to use this for electron interferometry and STEM-holography [7]. Advantages of using a grating as an amplitude-type beamsplitters over Moellenstedt biprisms in conventional electron holography is that (a) it preserves the symmetry of the probe, essentially creating multiple copies of it, (b) it loosens the coherent requirements of the initial electron beam, potentially enabling electron holography in an expanded range of instruments, (c) eliminates the voltage stability requirements of a biprism, and (d) allows for structured probes by incorporating additional holographic features into the grating. Nanostructured electron optics also can be used to implement new types of on-axis interferometric phase contrast in STEM (Figure 2). For example, in Matched Illumination-Detector Interferometry STEM (MIDI-STEM), a transverse phase modulation is introduced to a STEM probe using a nanostructured phase plate in the probe-defining condenser aperture [2,3]. The diffraction plane of the probe is imaged at each probe position. Virtual detector zones are defined on the fast imaging detector. Nonuniform phase introduced by the specimen across the probe results in intensity shifts between the pre-defined zones. For an appropriately defined phase plate, this can provide linear phase contrast at high resolutions in aberration-corrected STEM.

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Origins and demonstrations of electrons with orbital angular momentum

Abstract: One contribution of 14 to a theme issue 'Optical orbital angular momentum' .

Cited by 48 publications

References 74 publications

Electron vortices: Beams with orbital angular momentum

Electron vortices: Beams with orbital angular momentum

Optical orbital angular momentum

Electron Microscopy with Structured Electrons

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