Connect with us

Science

Scientists use trilayer graphene to observe more robust superconductivity – Phys.org

Published

 on


Harvard scientists use trilayer graphene to observe more robust superconductivity
Artist rendition of twisted trilayer graphene. Credit: Polina Shmatkova & Margarita Davydova

In 2018, the physics world was set ablaze with the discovery that when an ultrathin layer of carbon, called graphene, is stacked and twisted to a “magic angle,” that new double layered structure converts into a superconductor, allowing electricity to flow without resistance or energy waste. Now, in a literal twist, Harvard scientists have expanded on that superconducting system by adding a third layer and rotating it, opening the door for continued advancements in graphene-based superconductivity.

The work is described in a new paper in Science and can one day help lead toward superconductors that operate at higher or even close to . These superconductors are considered the holy grail of condensed matter physics since they would allow for tremendous technological revolutions in many areas including electricity transmission, transportation, and quantum computing. Most superconductors today, including the double layered graphene structure, work only at ultracold temperatures.

“Superconductivity in twisted graphene provides physicists with an experimentally controllable and theoretically accessible model system where they can play with the system’s properties to decode the secrets of high ,” said one of the paper’s co-lead authors Andrew Zimmerman, a postdoctoral researcher in working in the lab of Harvard physicist Philip Kim.

Graphene is a one-atom-thick layer of carbon atoms that is 200 times stronger than steel yet is extremely flexible and lighter than paper. It has almost always been known to be a good conductor of heat and electrical current but is notoriously difficult to handle. Experiments unlocking the puzzle of twisted bilayer graphene have been ongoing since MIT physicist Pablo Jarillo-Herrero and his group pioneered the emerging field of “twistronics” with their experiment in 2018 where they produced the graphene superconductor by twisting it to a magic angle of 1.1 degrees.

The Harvard scientists report successfully stacking three sheets of graphene and then twisting each of them at that magic angle to produce a three-layered structure that is not only capable of superconductivity but does so more robustly and at higher temperatures than many of the double-stacked . The new and improved system is also sensitive to an externally applied electric field that allows them to tune the level of superconductivity by adjusting the strength of that field.

“It enabled us to observe the superconductor in a new dimension and provided us with important clues about the mechanism that’s driving the superconductivity,” said the study’s other lead author Zeyu Hao, a Ph.D. student in the Graduate School of Arts and Sciences also working in the Kim Group.

One of those mechanisms has the theorists really excited. The trilayer system showed evidence that its superconductivity is due to between electrons as opposed to weak ones. If true, this can not only help open a path to high temperature superconductivity but possible applications in quantum computing.

“In most conventional superconductors, electrons move with a high speed and occasionally cross-paths and influence each other. In this case, we say their interaction effects are weak,” said Eslam Khalaf, a co-author on the study and postdoctoral fellow working in the lab of Harvard physics professor Ashvin Vishwanath. “While weakly interacting superconductors are fragile and lose superconductivity when heated to a few Kelvins, strong coupling superconductors are much more resilient but much less understood. Realizing strong coupling superconductivity in a simple and tunable system such as trilayer could pave the way to finally develop a theoretical understanding of strongly-coupled to help realize the goal of a high temperature, maybe even room temperature, superconductor.”

The researchers plan on continuing to explore the nature of this unusual superconductivity in further studies.

“The more we understand, the better we have chance to increase the superconducting transition temperatures,” said Kim.


Explore further

Physicists create tunable superconductivity in twisted graphene ‘nanosandwich’


More information:
“Electric field tunable superconductivity in alternating twist magic-angle trilayer graphene” Science, science.sciencemag.org/cgi/doi … 1126/science.abg0399

Citation:
Scientists use trilayer graphene to observe more robust superconductivity (2021, February 4)
retrieved 4 February 2021
from https://phys.org/news/2021-02-scientists-trilayer-graphene-robust-superconductivity.html

This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.

Let’s block ads! (Why?)



Source link

Continue Reading

Science

Dusty demise for NASA Mars lander in July; power dwindling – CGTN

Published

 on


A NASA spacecraft on Mars is headed for a dusty demise. 

The InSight lander is losing power because of all the dust on its solar panels. NASA said Tuesday it will keep using the spacecraft’s seismometer to register marsquakes until the power peters out, likely in July. Then flight controllers will monitor InSight until the end of this year, before calling everything off. 

“There really hasn’t been too much doom and gloom on the team. We’re really still focused on operating the spacecraft,” said Jet Propulsion Laboratory’s Bruce Banerdt, the principal scientist. 

Since landing on Mars in 2018, InSight has detected more than 1,300 marsquakes; the biggest one, a magnitude 5, occurred two weeks ago. 

It will be NASA’s second Mars lander lost to dust: A global dust storm took out Opportunity in 2018. In InSight’s case, it’s been a gradual gathering of dust, especially over the past year.

NASA’s two other functioning spacecraft on the Martian surface – rovers Curiosity and Perseverance – are still going strong thanks to nuclear power. The space agency may rethink solar power in the future for Mars, said planetary science director Lori Glaze, or at least experiment with new panel-clearing tech or aim for the less-stormy seasons.

InSight currently is generating one-tenth of the power from the sun that it did upon arrival. Deputy project manager Kathya Zamora Garcia said the lander initially had enough power to run an electric oven for one hour and 40 minutes; now it’s down to 10 minutes max. 

The InSight team had anticipated this much dust buildup, but hoped a gust of wind or dust devil might clean off the solar panels. That has yet to happen, despite several thousand whirlwinds coming close. 

“None of them have quite hit us dead-on yet enough to blow the dust off the panels,” Banerdt told reporters. 

Another science instrument, dubbed the mole, was supposed to burrow 16 feet (5 meters) underground to measure the internal temperature of Mars. But the German digger never got deeper than a couple of feet (a half-meter) because of the unexpected composition of the red dirt, and it finally was declared dead at the beginning of last year.

Adblock test (Why?)



Source link

Continue Reading

Science

Blood moon, big city: Skywatcher captures total lunar eclipse over New York (photos) – Space.com

Published

 on


The eclipsed moon burns red high above the bright lights of New York City in gorgeous photos captured by amateur astronomer Alexander Krivenyshev.

Krivenyshev, the president of WorldTimeZone.com, snapped images of the total lunar eclipse on Sunday night (May 15) from Guttenberg, New Jersey, which is across the Hudson River from the Big Apple. 

He persevered through cloudy conditions, Krivenyshev told Space.com via email, to get shots of the blood-red moon shining like a beacon in a light-polluted sky.

Related: Amazing photos of the Super Flower Blood Moon of 2022

A closeup of the eclipsed moon on May 15, 2022, as photographed by Alexander Krivenyshev. (Image credit: Alexander Krivenyshev, WorldTimeZone.com)

The eclipse began at 9:32 p.m EDT on Sunday (0132 GMT on May 16) when the moon nosed into the light part of Earth’s shadow, known as the penumbra, and ended five hours later. The total eclipse phase, in which the moon was completely darkened by Earth’s heavier umbral shadow, lasted 85 minutes, the longest of any lunar eclipse in 33 years.

Earth’s nearest neighbor temporarily turns a coppery red during total lunar eclipses. This “blood moon” effect is caused by Earth’s atmosphere, which bends some red light onto the lunar surface while scattering away shorter-wavelength light. (No sunlight is hitting the moon directly at this point, of course; Earth is blocking the sun from the moon’s perspective.)

Another series of shots of the total lunar eclipse over New York City, photographed by Alexander Krivenyshev on May 15, 2022.  (Image credit: Alexander Krivenyshev, WorldTimeZone.com)

Related stories:

Last weekend’s sky show was best observed from the Americas and parts of Western Europe and West Africa. It was the first total lunar eclipse of the year, but it won’t be the last; another one will occur on Nov. 8. The Nov. 8 lunar eclipse will be best observed from Australia, eastern Asia and the western United States. 

If you’re hoping to photograph the moon, or want to prepare for the next total lunar eclipse, check out our best cameras for astrophotography and best lenses for astrophotography. Our guides on how to photograph a lunar eclipse, and how to photograph the moon with a camera, also have some helpful tips to plan out your lunar photo session.

Editor’s Note: If you snap an amazing lunar eclipse photo (or your own eclipse webcast) and would like to share it with Space.com’s readers, send your photo(s), comments, and your name and location to spacephotos@space.com.

Mike Wall is the author of “Out There” (Grand Central Publishing, 2018; illustrated by Karl Tate), a book about the search for alien life. Follow him on Twitter @michaeldwall. Follow us on Twitter @Spacedotcom or on Facebook.  

Adblock test (Why?)



Source link

Continue Reading

Science

NASA's Mars InSight mission coming to an end as dust covers solar panels – CBC News

Published

 on


A NASA spacecraft on Mars is headed for a dusty demise.

The Insight lander is losing power because of all the dust on its solar panels. NASA said Tuesday it will keep using the spacecraft’s seismometer to register marsquakes until the power peters out, likely in July. Then flight controllers will monitor InSight until the end of this year, before calling everything off.

“There really hasn’t been too much doom and gloom on the team. We’re really still focused on operating the spacecraft,” said Jet Propulsion Laboratory’s Bruce Banerdt, the principal scientist.

Since landing on Mars in 2018, InSight has detected more than 1,300 marsquakes; the biggest one, a magnitude 5, occurred two weeks ago.

It will be NASA’s second Mars lander lost to dust: A global dust storm took out Opportunity in 2018. In InSight’s case, it’s been a gradual gathering of dust, especially over the past year.

WATCH | NASA scientists discuss InSight’s goals on Mars: [embedded content]

Rethinking solar power

NASA’s two other functioning spacecraft on the Martian surface — rovers Curiosity and Perseverance — are still going strong thanks to nuclear power.

The space agency may rethink solar power in the future for Mars, said planetary science director Lori Glaze, or at least experiment with new panel-clearing tech or aim for the less-stormy seasons.

InSight currently is generating one-tenth of the power from the sun that it did upon arrival.

Deputy project manager Kathya Zamora Garcia said the lander initially had enough power to run an electric oven for one hour and 40 minutes; now it’s down to 10 minutes max.

The InSight team anticipated this much dust buildup, but hoped a gust of wind or a dust devil might clean off the solar panels. That has yet to happen, despite several thousand whirlwinds coming close.

“None of them have quite hit us dead-on yet enough to blow the dust off the panels,” Banerdt told reporters.

Another science instrument, dubbed the mole, was supposed to burrow five metres underground to measure the internal temperature of Mars. But the German digger never got deeper than a half-metre because of the unexpected composition of the red dirt, and it finally was declared dead at the beginning of last year.

Adblock test (Why?)



Source link

Continue Reading

Trending