Lifeboat Foundation

A sheet of magic-angle twisted bilayer graphene can host novel topological phases of matter, a study has revealed.

Magic-angle twisted graphene, first discovered in 2018, is made from two sheets of graphene (a form of carbon consisting of a single layer of atoms in a honeycomb-like lattice pattern), layered atop one another, with one sheet twisted at precisely 1.05 degrees with respect to the other. The resulting bilayer has unusual electronic properties: for example, it can be made into an insulator or a superconductor depending on how many electrons are added.

The discovery launched a new field of research into magic-angle twisted graphene, known as “twistronics.” At Caltech, Stevan Nadj-Perge, assistant professor of applied physics and materials science, has been among the researchers leading the charge: in 2019, he and his colleagues directly imaged the electronic properties of magic-angle twisted graphene at atomic-length scales; and in 2020, they demonstrated that superconductivity in twisted bilayer graphene can exist away from the magic angle when coupled to a two-dimensional semiconductor.

Electrons inhabit a strange and topsy-turvy world. These infinitesimally small particles have never ceased to amaze and mystify despite the more than a century that scientists have studied them. Now, in an even more amazing twist, physicists have discovered that, under certain conditions, interacting electrons can create what are called ‘topological quantum states.’ This finding, which was recently published in the journal Nature, has implications for many technological fields of study, especially information technology.

Topological states of matter are particularly intriguing classes of quantum phenomena. Their study combines quantum physics with topology, which is the branch of theoretical mathematics that studies geometric properties that can be deformed but not intrinsically changed. Topological quantum states first came to the public’s attention in 2016 when three scientists—Princeton’s Duncan Haldane, who is Princeton’s Thomas D. Jones Professor of Mathematical Physics and Sherman Fairchild University Professor of Physics, together with David Thouless and Michael Kosterlitz—were awarded the Nobel Prize for their work in uncovering the role of topology in electronic materials.

“The last decade has seen quite a lot of excitement about new topological quantum states of electrons,” said Ali Yazdani, the Class of 1909 Professor of Physics at Princeton and the senior author of the study. “Most of what we have uncovered in the last decade has been focused on how electrons get these topological properties, without thinking about them interacting with one another.”

Assembling Lego-like, 2D heterostructures can give rise to emergent properties and functionalities very different from the intrinsic characteristics of the constituents.

Density functional theory (DFT)-based band-structure calculations can shed light on interfacial properties of different heterostructures.

South Korea’s Moon mission

The mission will circle the Moon for about a year at about 100 kilometers above the surface, searching for possible landing sites for future missions, conducting scientific research on the lunar environment, and testing space internet technology, South Korea’s Ministry of Science and ICT said in a statement. This mission will help prepare the country’s small space program for future exploration, as they hope to send a lander to the Moon by 2030.

Continue reading “South Korea just launched a rocket to orbit the Moon, a first for the country” »

Skin healing processes and spacewalk preparations filled the work schedule aboard the International Space Station on Friday. The Expedition 67 crew members are also readying a U.S. space freighter for its return to Earth next week.

Four astronauts aboard the orbiting lab practiced surgical techniques to heal wounds in microgravity on Friday in the Kibo laboratory module. The quartet split up in groups of two with NASA astronaut Bob Hines joining ESA (European Space Agency) Flight Engineer Samantha Cristoforetti for the first practice session during the morning. In the afternoon, NASA Flight Engineers Kjell Lindgren and Jessica Watkins began their session studying how to take biopsies and suture wounds inside the Life Science Glovebox.

During the middle of the day, the foursome had time set aside time for gathering frozen research samples inside science freezers and preparing them for departure back to Earth inside the SpaceX Dragon resupply ship. Dragon is due to leave the station on Aug. 18 loaded with over 4,000 pounds of station supplies and science experiments after 33 days docked to the Harmony module’s forward port. The commercial cargo craft will parachute to a splashdown off the coast of Florida the next day for retrieval by NASA and SpaceX personnel.

Sustained space exploration will require infrastructure that doesn’t currently exist: buildings, housing, rocket landing pads.

So, where do you turn for construction materials when they are too big to fit in your carry-on and there’s no Home Depot in outer space?

“If we’re going to live and work on another planet like Mars or the moon, we need to make concrete. But we can’t take bags of concrete with us—we need to use local resources,” said Norman Wagner, Unidel Robert L. Pigford Chair of Chemical and Biomolecular Engineering at the University of Delaware.

It’s an evolutionary simplification of the larynx.

A so-called evolutionary simplification of the larynx led to human speech. This trait is still present today. Researchers are unsure at what point in history it evolved.

Scientists have spotted the evolutionary modifications in the voice box that make humans able to speak compared to other primates. They did this through an examination of the voice box, or larynx, in 43 species of primates.

Continue reading “Scientists identify what makes humans able to speak compared to other primates” »

Circa 2010 face_with_colon_three

http://www.ted.com Stephen Wolfram, creator of Mathematica, talks about his quest to make all knowledge computational — able to be searched, processed and manipulated. His new search engine, Wolfram Alpha, has no lesser goal than to model and explain the physics underlying the universe.

Continue reading “Computing a theory of everything | Stephen Wolfram” »

A potentially better way to make oxygen for astronauts in space using magnetism has been proposed by an international team of scientists, including a University of Warwick chemist.

The conclusion is from new research on magnetic phase separation in microgravity published in npj Microgravity by researchers from the University of Warwick in the United Kingdom, University of Colorado Boulder and Freie Universität Berlin in Germany.

Keeping astronauts breathing aboard the International Space Station and other space vehicles is a complicated and costly process. As humans plan future missions to the Moon or Mars better technology will be needed.