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Category: computing – Page 681

New family of quasiparticles appears in graphene

Researchers identify Brown-Zak fermions in superlattices made from the carbon sheet.

Researchers at the University of Manchester in the UK have identified a new family of quasiparticles in superlattices made from graphene sandwiched between two slabs of boron nitride. The work is important for fundamental studies of condensed-matter physics and could also lead to the development of improved transistors capable of operating at higher frequencies.

In recent years, physicists and materials scientists have been studying ways to use the weak (van der Waals) coupling between atomically thin layers of different crystals to create new materials in which electronic properties can be manipulated without chemical doping. The most famous example is graphene (a sheet of carbon just one atom thick) encapsulated between another 2D material, hexagonal boron nitride (hBN), which has a similar lattice constant. Since both materials also have similar hexagonal structures, regular moiré patterns (or “superlattices”) form when the two lattices are overlaid.

If the stacked layers of graphene-hBN are then twisted, and the angle between the two materials’ lattices decreases, the size of the superlattice increases. This causes electronic band gaps to develop through the formation of additional Bloch bands in the superlattice’s Brillouin zone (a mathematical construct that describes the fundamental ideas of electronic energy bands). In these Bloch bands, electrons move in a periodic electric potential that matches the lattice and do not interact with one another.

World’s smallest atom-memory unit created

Faster, smaller, smarter and more energy-efficient chips for everything from consumer electronics to big data to brain-inspired computing could soon be on the way after engineers at The University of Texas at Austin created the smallest memory device yet. And in the process, they figured out the physics dynamic that unlocks dense memory storage capabilities for these tiny devices.

The research published recently in Nature Nanotechnology builds on a discovery from two years ago, when the researchers created what was then the thinnest storage device. In this new work, the researchers reduced the size even further, shrinking the cross section area down to just a single square nanometer.

Getting a handle on the physics that pack dense memory storage capability into these devices enabled the ability to make them much smaller. Defects, or holes in the material, provide the key to unlocking the high-density memory storage capability.

New psychology study provides insight into fundamental cognitive processes linked to dogmatism

Dogmatic individuals tend to form less accurate judgements thanks to a generic resistance to seeking out additional information, according to new research published in the Proceedings of the National Academy of Sciences (PNAS). The findings shed new light on the cognitive underpinnings of dogmatic worldviews.

“We have never been so free to decide if we have enough evidence about something or whether we should seek out further information from a reliable source before believing it,” explained study author Lion Schulz, a doctoral researcher in the Department of Computational Neuroscience at the Max Planck Institute for Biological Cybernetics.

“In turn, if we don’t check on quick and uncertain judgements, this can leave us quite vulnerable to misinformation. Understanding the mechanism behind such decisions and how different people approach them is therefore important when we try to understand the current societal climate.”

Amazon cloud-computing outage Wednesday triggered by effort to boost system’s capacity

Amazon acknowledged that the system failure was exacerbated by the co-dependencies its various services have on one another. The company had been trying to add capacity to its Amazon Kinesis service that customers use to process real-time data including video, audio and application logs. To resolve the issue, Amazon needed to restart a piece of its system it described as “many thousands of servers,” a lengthy process that had to be done gradually. But because other Amazon cloud services rely on Kinesis, including its Cognito authentication offering, they failed as well.

Physicists Successfully Modify a Semiconductor to Create a Superconductor

Three physicists in the Department of Physics and Astronomy at the University of Tennessee, Knoxville, together with their colleagues from the Southern University of Science and Technology and Sun Yat-sen University in China, have successfully modified a semiconductor to create a superconductor.

Professor and Department Head Hanno Weitering, Associate Professor Steve Johnston, and PhD candidate Tyler Smith were part of the team that made the breakthrough in fundamental research, which may lead to unforeseen advancements in technology.

Semiconductors are electrical insulators but conduct electrical currents under special circumstances. They are an essential component in many of the electronic circuits used in everyday items including mobile phones, digital cameras, televisions, and computers.

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