Using electron vortex beams to determine chirality of crystals in transmission electron microscopy

Juchtmans, Roeland; Béché, Armand; Abakumov, Artem M.; Batuk, Maria; Verbeeck, Jo

doi:10.1103/physrevb.91.094112

Cited by 76 publications

(59 citation statements)

References 31 publications

(39 reference statements)

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“…23(b), and the resulting diffraction pattern is always centrosymmetric. In contrast to this, the vortex probe circumvents Friedel's law, and non-centrosymmetric crystals produce non-centrosymmetric diffraction patterns [249,250]. This is because for the vortex wave functionψ(k), generically [Ṽ * ψ](q) = [Ṽ * ψ] * (−q), and opposite-q scatterings can have different probabilities, Fig.…”

Section: Elastic Interaction Of Vortex Electrons With Mattermentioning

confidence: 99%

See 1 more Smart Citation

Theory and applications of free-electron vortex states

Bliokh¹,

Иванов²,

Guzzinati³

et al. 2017

Physics Reports

304

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: Elastic Interaction Of Vortex Electrons With Mattermentioning

confidence: 99%

“…In Ref. [249] this method was demonstrated experimentally by focusing electron vortex beam on the three-fold screw axis of a Mn 2 Sb 2 O 7 crystal.…”

Section: Chirality In Crystalsmentioning

confidence: 99%

Theory and applications of free-electron vortex states

Bliokh¹,

Иванов²,

Guzzinati³

et al. 2017

Physics Reports

304

347

View full text Add to dashboard Cite

show abstract

“…Computing such differences in a simulation with zero magnetic fields merely yields a numerical noise around ten orders of magnitude smaller. The kink observed close to θ = 130 mrad appears near a higher order Laue zone [33].…”

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confidence: 99%

Elastic Scattering of Electron Vortex Beams in Magnetic Matter

2016

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Elastic scattering of electron vortex beams on magnetic materials leads to a weak magnetic contrast due to Zeeman interaction of orbital angular momentum of the beam with magnetic fields in the sample. The magnetic signal manifests itself as a redistribution of intensity in diffraction patterns due to a change of sign of the orbital angular moment. While in the atomic resolution regime the magnetic signal is most likely under the detection limits of present transmission electron microscopes, for electron probes with high orbital angular momenta, and correspondingly larger spatial extent, its detection is predicted to be feasible.Rapid developments in nanoengineering call for characterization methods capable to reach high spatial resolution. In this domain, the scanning transmission electron microscope (STEM) provides a broad scale of measurement techniques ranging from Z-contrast [1] or electron energy-loss elemental mapping [2], differential phase contrast (DPC) [3,4], via local electronic structure studies of single atoms [5] to counting individual atoms in nanoparticles [6]. As a specific case of high-spatial resolution electron energy loss spectroscopy, an electron magnetic circular dichroism (EMCD) method has been introduced [7] as an analogue to x-ray magnetic circular dichroism, which is a well established quantitative method of measuring spin and orbital magnetic moments in an elementselective manner [8,9].Recenly, the introduction of electron vortex beams (EVB) [10][11][12], i.e., beams with nonzero orbital angular momentum, aimed at probing EMCD at atomic spatial resolution. It was shown theoretically that EVBs need to be of atomic size in order to be efficient for magnetic studies [13][14][15]. Several methods of generating atomic size electron vortex beams have been proposed [16][17][18][19], yet an experimental demonstration of atomic resolution EMCD has not been presented in the literature.An alternative route to utilizing EVBs for magnetic measurements is based on Zeeman interaction between their angular momentum and the magnetic field in the sample. The Pauli equation for an electron with energy E in an electrostatic potential V (r) and a constant magnetic field B c readswhere −e is the electron charge, m is the electron mass, p = −i ∇ is the momentum operator,L andŜ are the orbital and spin angular momentum operators, and Ψ(r) is a two-component spinor wavefunction. The second term on the left hand side of Eq. 1 manifests a coupling between the magnetic field and the orbital and spin angular momenta of the electron beam. A previous study has indicated that the effect of spin on elastic scattering is very weak [20]. Moreover, generating intense spin polarized electron beams remains a technological challenge [21] and so far magnetic field mapping with spin-polarized electrons in the TEM could not be demonstrated. While the spin angular momentum of electrons in the propagation direction is at most 2 , EVBs can be generated with very high orbital angular momenta (OAM) [12,22,23], which permits an in...

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“…The fact that these EVBs carry OAM has led to the proposition and demonstration of many applications ranging from the measurement of magnetic properties with atomic resolution (Verbeeck et al, 2010;Rusz et al, 2014;Idrobo et al, 2016;Schachinger et al, 2017), the study of the dynamics of Landau states (Schattschneider, Schchinger et al, 2014;Schachinger et al, 2015), sample chirality (Juchtmans et al, 2015) and symmetry properties of plasmon resonances (Guzzinati et al, 2017), to the manipulation of nanoparticles . Despite the huge potential of EVBs and the fact that their creation and propagation through vacuum are well understood (Schattschneider & Verbeeck, 2011;Schattschneider et al, 2012;Schachinger et al, 2015), knowledge of their propagation through matter is still somewhat lacking.…”

Section: Introductionmentioning

confidence: 99%