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Don't underestimate undulating graphene: Unique electronics made possible by wavy patterns that channel electrons – Phys.org

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A theory by Rice University researchers suggests growing graphene on a surface that undulates like an egg crate would stress it enough to create a minute electromagnetic field. The phenomenon could be useful for creating 2D electron optics or valleytronics devices. Credit: Henry Yu/Rice University

Lay some graphene down on a wavy surface, and you’ll get a guide to one possible future of two-dimensional electronics. 

Rice University scientists put forth the idea that growing atom-thick on a gently textured surface creates peaks and valleys in the sheets that turn them into “pseudo-electromagnetic” devices.

The channels create their own minute but detectable magnetic fields. According to a study by materials theorist Boris Yakobson, alumnus Henry Yu and research scientist Alex Kutana at Rice’s George R. Brown School of Engineering, these could facilitate nanoscale like converging lenses or collimators. 

Their study appears in the American Chemical Society’s Nano Letters.

They also promise a way to achieve a Hall effect — a voltage difference across the strongly conducting graphene —that could facilitate valleytronics applications that manipulate how electrons are trapped in “valleys” in an .

Valleytronics are related to spintronics, in which a device’s memory bits are defined by an electron’s quantum spin state. But in valleytronics, electrons have degrees of freedom in the multiple momentum states (or valleys) they occupy. These can also be read as bits.

This is all possible because graphene, while it may be one of the strongest known structures, is pliable enough as it adheres to a surface during .

“Substrate sculpting imparts deformation, which in turn alters the material electronic structure and changes its optical response or ,” said Yu, now a postdoctoral researcher at Lawrence Livermore National Laboratory. “For sharper substrate features beyond the pliability of the material, one can engineer defect placements in the materials, which creates even more drastic changes in material properties.”

Yakobson compared the process to depositing a sheet of graphene on an egg crate. The bumps in the crate deform the graphene, stressing it in a way that creates an even without electrical or magnetic input.

“The endless designs of substrate shapes allow for countless optical devices that can be created, making possible 2-D electron optics,” Yakobson said. “This technology is a precise and efficient way of transmitting material carriers in 2-D electronic devices, compared to traditional methods.”


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More information:
Henry Yu et al, Electron Optics and Valley Hall Effect of Undulated Graphene, Nano Letters (2022). DOI: 10.1021/acs.nanolett.2c00103

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Don’t underestimate undulating graphene: Unique electronics made possible by wavy patterns that channel electrons (2022, March 23)
retrieved 24 March 2022
from https://phys.org/news/2022-03-dont-underestimate-undulating-graphene-unique.html

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

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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.

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

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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.  

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

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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.

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