A new physical quantity of electrons—orbital angular momentum—has been generated by Masaya Uchida and Akira Tonomura at the RIKEN Advanced Science Institute in Wako, Japan. The work, published today in the international science journal Nature1, could establish novel fields of research and lead to new electron microscopes.
“The ability of optical waves to spiral about their axis as they propagate, which can be described as corkscrew wavefronts, has already found a wide range of applications” explains Uchida.
A wave can be characterized by the shape of its wavefronts: imaginary surfaces that connect all points where the wave is at the same stage in its oscillatory cycle. In a conventional plane wave, these fronts are a series of flat surfaces oriented perpendicular to the direction of propagation.
Since electron waves act like optical waves, Uchida thought that spiraling electron waves were possible.
The researchers had to resolve a daunting technological challenge to generate the electrons with orbital angular momentum. A corkscrew wavefront is imprinted on an electron plane wave when it passes through a three-dimensional (3D) structure shaped into a single twist of the desired spiral. But since the height of the twist—determined by the wavelength of electron wave—is less than 100 nanometers, creating such a spiraling nanostructure is difficult.
The researchers simplified this problem by approximating the spiraling structure to several linear steps like a spiral ‘staircase’. They crushed the graphite from a pencil into thin films and placed them onto a carbon-coated copper grid. These fragments formed stacked layers resembling a spiral staircase.
To prove that the electrons gained orbital angular momentum as they passed through this simple 3D nanostructure, Uchida and Tonomura mixed the output wave with a second plane wave. They observed the characteristic ‘Y’-shaped defect to the parallel-lines pattern that is expected when two plane waves interfere. Measuring the transfer of momentum from the electrons to matter, however, could be a more direct way of identifying spiraling electron waves in the future, the researchers note.
“The next stage of the research is to produce wavefronts with various structure types,” says Uchida. “Just as there are many types of pasta, so there are many shapes of electron wave.”For more information, please contact:
Black hole spin cranks-up radio volume
15.01.2018 | National Institutes of Natural Sciences
The universe up close
15.01.2018 | Georg-August-Universität Göttingen
What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...
For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.
Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...
At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.
No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...
Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.
Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...
The oceans are the largest global heat reservoir. As a result of man-made global warming, the temperature in the global climate system increases; around 90% of...
08.01.2018 | Event News
11.12.2017 | Event News
08.12.2017 | Event News
16.01.2018 | Materials Sciences
16.01.2018 | Life Sciences
16.01.2018 | Health and Medicine