Researchers design a graphene-based tunable beam splitter

Researchers from France, South Korea, and Japan have created a graphene-based “beam splitter” for electronic currents. The tunable device’s operation is directly comparable to that of an optical interferometer. The team believes that the technology could enable electron interferometry to be used in nanotechnology and quantum computing.
Schematic representation of the p − n junction imageQuantum Hall valley splitter - schematic representation of the p − n junction. Image from article

An optical interferometer splits a beam of light in two, sending each beam along a different path before recombining the beams at a detector. The measured interference of the beams at the detector can be used to detect tiny differences in the lengths of the two paths. Recently, physicists have become interested in doing a similar thing with currents of electrons in solid-state devices, taking advantage of the fact that electrons behave similarly to waves in the quantum world.

Researchers manage to induce “artificial magnetic texture” in graphene

An international research team, led by the University at Buffalo, has reported an advancement that could help give graphene magnetic properties. The researchers describe in their work how they paired a magnet with graphene, and induced what they describe as “artificial magnetic texture” in the nonmagnetic material.

Induced magnetism in graphene could also promote spintronics imageThe image shows eight electrodes around a 20-nanometer-thick magnet (white rectangle) and graphene (white dotted line). Credit: University at Buffalo.

“Independent of each other, graphene and spintronics each possess incredible potential to fundamentally change many aspects of business and society. But if you can blend the two together, the synergistic effects are likely to be something this world hasn’t yet seen,” says lead author Nargess Arabchigavkani, who performed the research as a PhD candidate at UB and is now a postdoctoral research associate at SUNY Polytechnic Institute.

University of Washington team finds that carefully constructed stacks of graphene can exhibit highly correlated electron properties

A research team led by the University of Washington recently reported that carefully constructed stacks of graphene can exhibit highly correlated electron properties. The team also found evidence that this type of collective behavior likely relates to the emergence of exotic magnetic states.

“We’ve created an experimental setup that allows us to manipulate electrons in the graphene layers in a number of exciting new ways,” said co-senior author Matthew Yankowitz, a UW assistant professor of physics and of materials science and engineering. Yankowitz led the team with co-senior author Xiaodong Xu, a UW professor of physics and of materials science and engineering.

Doped graphene shows promise for sodium-ion batteries

Scientists at EPFL have recently published a research that could open up new pathways to boosting the capacity of sodium-ion batteries. “Lithium is becoming a critical material as it is used extensively in cell-phones and car batteries, while, in principle, sodium could be a much cheaper, more abundant alternative,” says Ferenc Simon, a visiting scientist in the group of László Forró at EPFL. “This motivated our quest for a new battery architecture: sodium doped graphene.”

Since sodium is far more abundant than lithium, and the risk of fire is much lower with this battery chemistry, it is considered a potentially viable replacement to current lithium-ion technology. But sodium also has much lower energy density than lithium, which has so far limited uptake, particularly in the electric vehicle and consumer electronics segments, where the physical size of the battery is a deciding factor. EPFL's new work uses graphene to address this issue.

Princeton team detects a cascade of electronic transitions in "magic-angle" twisted bilayer graphene

A team of researchers at Princeton has looked for the origins of the unusual behavior known as magic-angle twisted bilayer graphene, and detected signatures of a cascade of energy transitions that could help explain how superconductivity arises in this material.

"This study shows that the electrons in magic-angle graphene are in a highly correlated state even before the material becomes superconducting, "said Ali Yazdani, Professor of Physics and the leader of the team that made the discovery. "The sudden shift of energies when we add or remove an electron in this experiment provides a direct measurement of the strength of the interaction between the electrons."

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