Prerequisites for a Cc/Cs-corrected ultrahigh-resolution TEM

Haider, Max; Müller, Heiko; Uhlemann, Stephan; Żach, J.; Loebau, Ulrich; Hoeschen, R

doi:10.1016/j.ultramic.2007.07.007

Cited by 100 publications

(53 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Early attempts for working with a plurality of holograms have shown limited success because of an insufficiently stable electron wave front [13]. This appears to have changed significantly with the increased overall stability of electron microscopes that were designed to house an aberration corrector [14].…”

Section: Article In Pressmentioning

confidence: 99%

Approaching routine 2π/1000 phase resolution for off-axis type holography

Voelkl¹,

Tang²

2010

Ultramicroscopy

View full text Add to dashboard Cite

Section: Article In Pressmentioning

confidence: 99%

Approaching routine 2π/1000 phase resolution for off-axis type holography

Voelkl¹,

Tang²

2010

Ultramicroscopy

View full text Add to dashboard Cite

“…Correction of chromatic aberration is now also possible [11] and this will result in instruments that produce images with a vastly improved signal-to-noise ratio, both in conventional and Lorentz imaging modes. With special objective lens designs, it will become possible in the near future to have both spherical and chromatic aberration corrected with a field free sample environment; this should allow for simultaneous high resolution and Lorentz imaging.…”

Section: Some Remarks On the Future Of Ltem And Summarymentioning

confidence: 99%

Recent Progress in Lorentz Transmission Electron Microscopy

Graef

2009

ESOMAT 2009 - 8th European Symposium on Martensitic Transformations

View full text Add to dashboard Cite

Abstract. After a brief review of the basic methods of Lorentz transmission electron microscopy (LTEM), including the Transport-of-Intensity formalism for phase reconstruction, we present a few examples of the application of LTEM to multiferroic materials, in this case ferromagnetic shape memory alloys. We discuss observations of magnetic domain walls pinned to anti-phase boundaries in Ni2MnGa, and domain wall behavior under an in-situ applied magnetic field in Fe-Pd-Co. Lorentz Microscopy: a Brief IntroductionIt is one of the primary goals of transmission electron microscopy (TEM) to determine quantitatively the structure and chemistry of solids. For a periodic structure, this involves determination of the content of the unit cell (atom types and positions). For magnetic materials, this includes determination of the local magnetization state. The characterization of magnetic microstructures is a complex problem, since it involves, in principle, the determination of a three-dimensional (3-D) vector field, i.e., the magnetization M(r), or the induction B(r).Lorentz TEM (or LTEM) relies on the fact that a high energy beam electron is deflected by the magnetic induction inside and around the sample. The deflection angle for a uniformly magnetized foil can be computed from a simple momentum balance [1] and is given by θ L = C L B ⊥ t, with C L = eλ/h, λ the electron wavelength, B ⊥ the induction component normal to the beam, and t the foil thickness. This beam deflection is usually about two orders of magnitude smaller than a typical Bragg angle, which means that the magnetization state in a foil must be studied by analyzing the fine-structure or splitting of the transmitted beam. The primary method to detect small deflections is to defocus the imaging lens, i.e., to look at a plane below or above the sample, so that the lateral shift of the deflected electrons can be measured; the larger the defocus, the larger the lateral shift and, hence, the easier the measurement. However, the larger the defocus, the more blurred the resulting image becomes, so that there is a practical limit to the amount of defocus that will produce interpretable magnetic contrast.The Lorentz deflection angle can be converted into a magnetic phase gradient [2] by means of the relation ∇ϕ m = 2πkθ L e, where k = 1/λ and e is a unit vector. Integrating this relation and substituting typical numerical values shows that magnetic films should normally be regarded as strong, albeit slowly varying, phase objects. It was shown by Aharonov and Bohm [3] that the total phase shift of an electron wave traveling through a magnetic material consists of two contributions (r ⊥ is a vector in the plane normal to the beam): a

show abstract

“…Aberration correctors consist of precise arrangements of multiple electrodes and magnetic solenoids, each of which must be supplied with well-controlled, highly-stable voltages and currents [9]. Proper use of an aberration corrected microscope requires time for alignment, and the fully corrected state is only valid for relatively short periods of time [10] although practical sub-Ångstrom imaging is possible for hours with small corrections applied manually by the operator.…”

Section: Introductionmentioning

confidence: 99%

Aberration corrected STEM by means of diffraction gratings

Linck¹,

Ercius

Pierce

et al. 2017

Ultramicroscopy

View full text Add to dashboard Cite

Abstract:In the past 15 years, the advent of aberration correction technology in electron microscopy has enabled materials analysis on the atomic scale. This is made possible by complex arrangements of multipole electrodes and magnetic solenoids to compensate the aberrations inherent to any focusing element of an electron microscope. Here, we describe an alternative method to correct for the spherical aberration of the objective lens in a scanning transmission electron microscopy (STEM) using a passive, nanofabricated diffractive optical element. This holographic device is installed in the probe forming aperture of a conventional electron microscope and can be designed to remove arbitrarily complex aberrations from the electron's wave front. In this work, we show a proof of principle experiment that demonstrates successful correction of the spherical aberration in STEM by means of such a grating corrector (GCOR). Our GCOR enables us to record aberration-corrected high-resolution HAADF STEM images, although yet without any improvement in probe current and resolution. Author Contact Information:Dr. Martin Linck, CEOS GmbH, Englerstr. 28, D-69126 Heidelberg, Germany

show abstract

Prerequisites for a Cc/Cs-corrected ultrahigh-resolution TEM

Cited by 100 publications

References 5 publications

Approaching routine 2π/1000 phase resolution for off-axis type holography

Approaching routine 2π/1000 phase resolution for off-axis type holography

Recent Progress in Lorentz Transmission Electron Microscopy

Aberration corrected STEM by means of diffraction gratings

Contact Info

Product

Resources

About