Tag: Benjamin McMorran

Electron Diffraction in a Scanning Electron Microscope

Presenter : Alexander Schachtner

Mentor : Benjamin McMorran

Major : Physics

Poster 4

We use focused ion beam nanofabrication to manufacture forked diffraction gratings capable of producing electron beams with helical wavefronts and orbital angular momentum (OAM). A vast number of unique beam modes carrying OAM can be produced through manipulation of grating fork number or position. Generally these gratings are milled such that they produce a phase shift in the beam and are used with high energy electrons (300keV) in a TEM to investigate the quantum or magnetic properties of the electron or image magnetic materials. Our latest work focuses on manufacturing gratings that produce only an amplitude shift, which opens up imaging capability to lower energy electrons (5-30 keV) and thus expands their use to a wider range of commercially available SEMs. We use these amplitude gratings to show the relationship between the number/position of forks and OAM inherited by the beam. This work could lead to advances in imaging capability, and also creates a widely accessible and scalable demonstration of the quantum properties of the electron which can be leveraged by any science program with SEM access.

Electron Vortex Beaks With Magnetic Diffraction Gratings

Presenter: Simon Swifter

Faculty Mentor: Benjamin McMorran

Presentation Type: Poster 41

Primary Research Area: Science

Major: Physics, Mathematics

The purpose of this study is to produce and characterize electron vortex beams created by a diffraction grating formed by a magnetization texture. In the past, electrons vortex beams have been produced using nano-fabricated physical diffraction gratings placed in a Transmission Electron Microscope. Professor Benjamin McMorran (University of Oregon) is an expert in the production of these electron beams with a spiraling wave front, or vortex beams. Our objective is to achieve the same vortex beams by instead utilizing magnetic materials as a diffraction grating. In thin samples, Iron Gadolinium (FeGd) has sinusoidal varying magnetic domains with regularly occurring fork defects that make it ideal for use in creating electron vortex beams. Our plan is to find an area where the domains in a sample of FeGd are forked appropriately, and to observe and image the diffraction patterns caused when electrons are transmitted through those points.

Transforming the Electron Microscope into an Electron Interferometer

Presenter(s): Gino Carrillo − Physics, Mathematics

Faculty Mentor(s): Benjamin McMorran

Poster 14

Research Area: Physics

In 1924 during the birth of quantum mechanics, Louis de Broglie proposed that microscopic particles such as the electron exhibit wave-like characteristics. Within a few years, electron scattering experiments were being conducted which led to the confirmation of de Broglie’s matter wave hypothesis. This discovery led to the birth of electron optics which includes electron microscopy and interferometry. Arguably the most important component in either field is the electron source. Electron interferometry in particular requires a high quality electron source. Therefore, much work has been devoted to developing the electron source. Instead of improving the electron source, another approach can be taken which is more cost effective. By combining the fields of electron microscopy and interferometry, I will demonstrate that it is possible to conduct electron interferometric experiments within a low coherence Transmission Electron Microscope (TEM). This implies that TEM’s all around the world with lower quality sources can be used for new applications, thus extending its capabilities in a cost effective manner. This is accomplished by using nanofabricated gratings which are installed in the TEM to act as the interferometer’s beam splitter. The optics within the TEM are then used to interfere the diffracted beams giving rise to a path separated interferometer.