from the world's big
Physicists solve a 140-year-old mystery
Scientists discover the inner workings of an effect that will lead to a new generation of devices.
- Researchers discover a method of extracting previously unavailable information from superconductors.
- The study builds on a 19th-century discovery by physicist Edward Hall.
- The research promises to lead to a new generation of semiconductor materials and devices.
New research, led by IBM, made a breakthrough in resolving a mystery that has baffled physicists for 140 years. It promises to lead to a new generation of semiconductor materials and devices that use them.
The invention of semiconductors was instrumental in bringing on our digital age. You can find these electricity-carrying substances in your smartphone and computer. An improvement in this field could have major ramifications for future gadgetry.
In 1879, the American physicist Edward Hall discovered the Hall effect, showing that you can measure how electricity in a conductor flows. He found that because a magnetic field deflects the movement of electronic charges in a conductor, you can measure the amount of that deflection. This number will describe the voltage perpendicular (or transverse) to the flow of charge.
Modern researchers recognized, that you can also make Hall effect measurements using light in so-called photo-Hall experiments that generate multiple carriers (or electron-hole pairs) in superconductors. Unfortunately, while the Hall voltage provides crucial information about these charge carriers in a semiconductor, it is limited to the properties of the dominant (or majority) charge carrier, explain contributing authors Oki Gunawan and Doug Bishop in a post on IBM's research blog.
Figuring out the information about both the majority and minority charge carriers, which impact changes in conductivity, would be key to advancing applications utilizing light, including optoelectronic devices like solar cells, LEDs, and lasers as well as artificial intelligence tech.
Now a new formula and technique for getting both the majority and minority carrier information was developed by researchers from KAIST (Korea Advanced Institute of Science and Technology), KRICT (Korea Research Institute of Chemical Technology), Duke University, and IBM.
The method, dubbed Carrier-Resolved Photo Hall (CRPH), measurement, can simultaneously extract information about the majority and minority carriers like density and mobility, carrier lifetimes and lengths of diffusion. In fact, compared to the three parameters of measurement traditionally derived by engaging the Hall effect, the novel technique can get up to seven parameters of information.
Credit: Gunawan/Nature magazine
The approach also takes advantage of a tool developed by IBM called the parallel dipole line (PDL) trap, which generates an oscillating magnetic field. It works as an ideal system for photo-Hall experiments because of the large amount of space it allocates for sample illumination.
If you'd like to dive more into the subject, check out the new study published in Nature magazine.
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Construction of the $500 billion dollar tech city-state of the future is moving ahead.
- The futuristic megacity Neom is being built in Saudi Arabia.
- The city will be fully automated, leading in health, education and quality of life.
- It will feature an artificial moon, cloud seeding, robotic gladiators and flying taxis.
The Red Sea area where Neom will be built:
Saudi Arabia Plans Futuristic City, "Neom" (Full Promotional Video)<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="c646d528d230c1bf66c75422bc4ccf6f"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/N53DzL3_BHA?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span>
Frequent shopping for single items adds to our carbon footprint.
- A new study shows e-commerce sites like Amazon leave larger greenhouse gas footprints than retail stores.
- Ordering online from retail stores has an even smaller footprint than going to the store yourself.
- Greening efforts by major e-commerce sites won't curb wasteful consumer habits. Consolidating online orders can make a difference.
A pile of recycled cardboard sits on the ground at Recology's Recycle Central on January 4, 2018 in San Francisco, California.
Photo by Justin Sullivan/Getty Images<p>A large part of the reason is speed. In a competitive market, pure players use the equation, <em>speed + convenience</em>, to drive adoption. This is especially relevant to the "last mile" GHG footprint: the distance between the distribution center and the consumer.</p><p>Interestingly, the smallest GHG footprint occurs when you order directly from a physical store—even smaller than going there yourself. Pure players, such as Amazon, are the greatest offenders. Variables like geographic location matter; the team looked at shopping in the UK, the US, China, and the Netherlands. </p><p>Sadegh Shahmohammadi, a PhD student at the Netherlands' Radboud University and corresponding author of the paper, <a href="https://www.cnn.com/2020/02/26/tech/greenhouse-gas-emissions-retail/index.html" target="_blank">says</a> the above "pattern holds true in countries where people mostly drive. It really depends on the country and consumer behavior there."</p><p>The researchers write that this year-and-a-half long study pushes back on previous research that claims online shopping to be better in terms of GHG footprints.</p><p style="margin-left: 20px;">"They have, however, compared the GHG emissions per shopping event and did not consider the link between the retail channels and the basket size, which leads to a different conclusion than that of the current study."</p><p>Online retail is where convenience trumps environment: people tend to order one item at a time when shopping on pure player sites, whereas they stock up on multiple items when visiting a store. Consumers will sometimes order a number of separate items over the course of a week rather than making one trip to purchase everything they need. </p><p>While greening efforts by online retailers are important, until a shift in consumer attitude changes, the current carbon footprint will be a hard obstacle to overcome. Amazon is trying to have it both ways—carbon-free and convenience addicted—and the math isn't adding up. If you need to order things, do it online, but try to consolidate your purchases as much as possible.</p><p>--</p><p><em>Stay in touch with Derek on <a href="http://www.twitter.com/derekberes" target="_blank">Twitter</a>, <a href="https://www.facebook.com/DerekBeresdotcom" target="_blank">Facebook</a> and <a href="https://derekberes.substack.com/" target="_blank">Substack</a>. His next book is</em> "<em>Hero's Dose: The Case For Psychedelics in Ritual and Therapy."</em></p>
Chronic irregular sleep in children was associated with psychotic experiences in adolescence, according to a recent study out of the University of Birmingham's School of Psychology.