The dynamic behavior of electrons in magnetic fields is crucial for understanding physical processes, such as the quantum Hall effect, which are important in many areas of solid state physics, including electrical conductivity. Yet, there is much that remains unknown about exactly how electrons behave in a magnetic field.
In research published today in Nature Communications, researchers Franco Nori and Konstantin Bliokh from the RIKEN Center for Emergent Matter Science in Japan, in collaboration with an experimental team in Austria, have made the first direct observations of free-electron Landau states—a form of quantized states that electrons adopt when moving through a magnetic field—and found that the internal rotational dynamics of quantum electrons, or how they move through the field, is surprisingly different from the classical model, and in line with recent quantum-mechanical predictions made at RIKEN.
The experimental team used a transmission electron microscope to generate nanometer-sized electron vortex beams in which the electrons had a variety of quantum angular-momentum states, and then analyzed the beam propagation to reconstruct the rotational dynamics of the electrons in different Landau states.
According to classical physics, the electrons should rotate uniformly at what is called the cyclotron frequency, the frequency adopted by a charged particle moving through a magnetic field.
Remarkably, what the researchers discovered is that in fact, depending on the quantum number describing the angular momentum, the electrons rotated in three different ways with zero frequency, the cyclotron frequency, and the Larmor frequency, which is half the cyclotron frequency.
This shows that the rotational dynamics of the electrons are more complex and intriguing than was once believed.
According to Franco Nori, who leads the RIKEN team, "This is a very exciting finding, and it will contribute to a better understanding of the fundamental quantum features of electrons in magnetic fields, and help us to reach a better understanding of Landau states and various related physical phenomena."
Jens Wilkinson | Eurek Alert!
Graphene microphone outperforms traditional nickel and offers ultrasonic reach
27.11.2015 | Institute of Physics
Tracking down the 'missing' carbon from the Martian atmosphere
25.11.2015 | California Institute of Technology
Planet Earth experienced a global climate shift in the late 1980s on an unprecedented scale, fuelled by anthropogenic warming and a volcanic eruption, according to new research published this week.
Scientists say that a major step change, or ‘regime shift’, in the Earth’s biophysical systems, from the upper atmosphere to the depths of the ocean and from...
The Fraunhofer Institute for Solar Energy Systems ISE has installed 70 photovoltaic modules on the outer façade of one of its lab buildings. The modules were...
Nerve cells cover their high energy demand with glucose and lactate. Scientists of the University of Zurich now provide new support for this. They show for the first time in the intact mouse brain evidence for an exchange of lactate between different brain cells. With this study they were able to confirm a 20-year old hypothesis.
In comparison to other organs, the human brain has the highest energy requirements. The supply of energy for nerve cells and the particular role of lactic acid...
In laser material processing, the simulation of processes has made great strides over the past few years. Today, the software can predict relatively well what will happen on the workpiece. Unfortunately, it is also highly complex and requires a lot of computing time. Thanks to clever simplification, experts from Fraunhofer ILT are now able to offer the first-ever simulation software that calculates processes in real time and also runs on tablet computers and smartphones. The fast software enables users to do without expensive experiments and to find optimum process parameters even more effectively.
Before now, the reliable simulation of laser processes was a job for experts. Armed with sophisticated software packages and after many hours on computer...
Researchers at Heidelberg University have devised a new way to study the phenomenon of magnetism. Using ultracold atoms at near absolute zero, they prepared a...
30.11.2015 | Event News
25.11.2015 | Event News
17.11.2015 | Event News
30.11.2015 | Ecology, The Environment and Conservation
30.11.2015 | Event News
30.11.2015 | Power and Electrical Engineering