Connect with us

Featured

Graphene gets a second gig

Berkeley Lab scientists tap into graphene’s hidden talent as an electrically tunable superconductor, insulator, and magnetic device for the advancement of quantum information science

Published

on

Guorui Chen/Berkeley Lab

Ever since graphene’s discovery in 2004, scientists have looked for ways to put this talented, atomically thin 2D material to work. Thinner than a single strand of DNA yet 200 times stronger than steel, graphene is an excellent conductor of electricity and heat, and it can conform to any number of shapes, from an ultrathin 2D sheet, to an electronic circuit.  

Last year, a team of researchers led by Feng Wang, a faculty scientist in Berkeley Lab’s Materials Sciences Division and a professor of physics at UC Berkeley, developed a multitasking graphene device that switches from a superconductor that efficiently conducts electricity, to an insulator that resists the flow of electric current, and back again to a superconductor.

Now, as reported in the journal Nature, the researchers have tapped into their graphene system’s talent for juggling not just two properties, but three: superconducting, insulating, and a type of magnetism called ferromagnetism. The multitasking device could make possible new physics experiments, such as research in the pursuit of an electric circuit for faster, next-generation electronics like quantum computing technologies. 

“So far, materials simultaneously showing superconducting, insulating, and magnetic properties have been very rare. And most people believed that it would be difficult to induce magnetism in graphene, because it’s typically not magnetic. Our graphene system is the first to combine all three properties in a single sample,” said Guorui Chen, a postdoctoral researcher in Wang’s Ultrafast Nano-Optics Group at UC Berkeley, and the study’s lead author. 

Using electricity to turn on graphene’s hidden potential

Graphene has a lot of potential in the world of electronics. Its atomically thin structure, combined with its robust electronic and thermal conductivity, “could offer a unique advantage in the development of next-generation electronics and memory storage devices,” said Chen, who also worked as a postdoctoral researcher in Berkeley Lab’s Materials Sciences Division at the time of the study.

The problem is that the magnetic materials used in electronics today are made of ferromagnetic metals, such as iron or cobalt alloys. Ferromagnetic materials, like the common bar magnet, have a north and a south pole. When ferromagnetic materials are used to store data on a computer’s hard disk, these poles point either up or down, representing zeros and ones – called bits.     

Graphene, however, is not made of a magnetic metal – it’s made of carbon. So the scientists came up with a creative workaround. 

They engineered an ultrathin device, just 1 nanometer in thickness, featuring three layers of atomically thin graphene. When sandwiched between 2D layers of boron nitride, the graphene layers – described as trilayer graphene in the study – form a repeating pattern called a moiré superlattice.

By applying electrical voltages through the graphene device’s gates, the force from the electricity prodded electrons in the device to circle in the same direction, like tiny cars racing around a track. This generated a forceful momentum that transformed the graphene device into a ferromagnetic system. 

More measurements revealed an astonishing new set of properties: The graphene system’s interior had not only become magnetic but also insulating; and despite the magnetism, its outer edges morphed into channels of electronic current that move without resistance. Such properties characterize a rare class of insulators known as Chern insulators, the researchers said.

Even more surprising, calculations by co-author Ya-Hui Zhang of the Massachusetts Institute of Technology revealed that the graphene device has not just one, but two conductive edges, making it the first observed “high-order Chern insulator,” a consequence of the strong electron-electron interactions in the trilayer graphene. 

Scientists have been in hot pursuit of Chern insulators in a field of research known as topology, which investigates exotic states of matter. Chern insulators offer potential new ways to manipulate information in a quantum computer, where data is stored in quantum bits, or qubits. A qubit can represent a one, a zero, or a state in which it is both a one and a zero at the same time.

“Our discovery demonstrates that graphene is an ideal platform for studying different physics, ranging from single-particle physics, to superconductivity, and now topological physics to study quantum phases of matter in 2D materials,” Chen said. “It’s exciting that we can now explore new physics in a tiny device just 1 millionth of a millimeter thick.”

The researchers hope to conduct more experiments with their graphene device to have a better understanding of how the Chern insulator/magnet emerged, and the mechanics behind its unusual properties.  

Researchers from Berkeley Lab; UC Berkeley; Stanford University; SLAC National Accelerator Laboratory; Massachusetts Institute of Technology; China’s Shanghai Jiao Tong University, Collaborative Innovation Center of Advanced Microstructures, and Fudan University; and Japan’s National Institute for Materials Science participated in the work.

This work was supported by the Center for Novel Pathways to Quantum Coherence in Materials, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science.

Featured

How retailers must respond to life under lockdown

Published

on

As businesses settle into lockdown, South Africa’s largest second-hand retailer, Cash Crusaders offer other retail businesses – that have also been forced to close, some advice and recommendations on preparing for, and managing through the lockdown. The group that have been operating for over 20 years with over 220 stores nationwide, also offer advice on considerations retail store owners – and other businesses, should make as the country makes their COVID-19 economic recovery.

Follow the rules

Ensure that you follow the rules set out by our President for the lockdown. As bitter as this pill may be to swallow, the longer-term benefits for our country and our businesses far outweigh the frustration and anxiety you may be feeling now. This is not a time to break the rules. #StayAtHome. It is a time to practice human responsibility, not complain about Human Rights being compromised. Countries who initially implemented loosely managed lockdowns, have had to extend to get the pandemic under control, so strict rules from the get-go will prevail in the fight against the virus. 

Secure your stores

By now you should’ve secured your valuable goods and should have ensured all your security systems are in good working order. If you haven’t already, make sure your security companies have your correct contact information. Make sure your necessary insurance cover is up to date.

Keep your staff informed

They are and continue to be your most important asset!

By now, you may have needed to investigate UIF benefits to compensate for your employees loss of income. The Minister of Employment and Labour, T.W Nxesi has recently announced measures that the Department will put in place under the current special circumstance relating to the Corona virus (COVID-19) and its impact on UIF contributors.

The Temporary Employee/Employer Relief Scheme (TERS) has been set up under the auspices of the Unemployment Insurance Fund (UIF). Employers apply for the TERS on behalf of its employees. 

The TERS has two distinct advantages over UIF 

  • All employees qualify for up to 3 months of benefits, irrespective of how long they have contributed to the UIF and 
  • TERS will not pay any employee less than the minimum wage.

You can benefit from the TERS by sending an email to covid19ters@labour.gov.za. Applicants will then receive an automated response which outlines the steps you will need to take, as well as the details surrounding them – including the requirements to claim benefits. During the lockdown period, the Department of Labour will not accept manual applications (to reduce physical contact and risk of the virus spreading), this is to reduce contact between people to curtail the spread of the pandemic. A hotline number has been created by the UIF (012-337 1997) for Covid–19 TERS Benefit enquiries during the lockdown period. 

Be sure to be calm when addressing any concerns with your team – they are anxious and nervous of what the eventuality of this outbreak may be.

Communicate with your bank

Make sure you’ve been in touch with your bank (as they are still operational) and discuss any loan repayment relief or postponement over the lockdown period (the banks have termed this a “payment holiday”). Work with them on a cash flow plan as once the lockdown has lifted, trading businesses will need liquid cash.

Contact your landlord

Ensure you’ve connected with your landlord to discuss and agree on any possible repayment or rent relief/payment holiday they may be able to offer you. Keep the channels of communications open with your landlord and bank – rather over-communicate than not communicate enough.

Keep communication open with your customers

The country may be on shutdown, but the internet isn’t. Communicate with your teams and customers by whatever necessary and relevant communication channels you have available to you – website, social media, PR/Marketing teams, newsletter dissemination etc.

Use this time wisely

Amidst all the chaos this time brings, there is also a silver lining. We all have time at this stage, but how many of us make valuable use of that time? Particularly when it comes to family.  Business is demanding most times so with a forced shutdown of business it give you the time to spend with your family, catch up on outdated maintenance around the house and a period of rest. This lockdown period will also afford you uninterrupted strategy time. Take the time to reflect on areas of your business you can improve or evolve. Strategise ways to do things better or differently. Use the resource available via your own business network as well as the countless online content that is available, to work on a plan for the way forward. Consider your financial, loan and other business administration processes you have in place and look at new ways to optimise the channels and areas you’re working with or within. A host of online learning facilities offer short courses – perhaps consider upskilling yourself or members of your team by signing up for one of these too.

“These are some of the steps we’ve taken within our own organisation,” says Sean Stegmann, CEO of Cash Crusaders. “Having been in this business for as long as we have has afforded us the wealth of experience we’re able to share with our franchisees and other retail business owners to help navigate the next few weeks and recovery period,” he says. “Take it one day at a time and know that the decisions we’re being forced to make today will mean a future for us tomorrow, both in business and in health!,” he concludes

Continue Reading

Featured

Vodacom cuts cost of smallest bundle by 40%

The country’s largest mobile operator has kept to a promise made last month to slash the price of entry-level data packages

Published

on

Vodacom has cut the data price of its lowest-cost bundle by 40%, reducing the price of a 50MB 30-day bundle from R20 to to R12. This follows from the operator’s promise in March, when it announced a 33% cut in the cost of 1GB bundles, to reduce prices of all smaller bundles by up to 40%.

Vodacom’s various 30-day data bundle prices will be cut across all of its channels, with the new pricing as follows:

30-day bundle size New Price Reduction
50MB R12 40%
150MB R29 33%
325MB R55 33%
500MB R79 21%
1GB R99 34%
3GB R229 23%
5GB R349 14%
10GB R469 22%
20GB R699 31%

Vodacom confirmed it will provide free data to access essential services through Vodacom’s zero-rated platform ConnectU with immediate effect. The value of these initiatives, it says, is R2.7-billion over the next year.

“Vodacom can play a critical role in supporting society during this challenging time and we’re committed to doing whatever we can to help customers stay connected,” says Jorge Mendes, Chief Officer of Vodacom’s Consumer Business Unit. “Since we started our pricing transformation strategy three years ago, our customers have benefitted from significant reductions in data prices and the cost of voice calls. Over the same period, we invested over R26 billion in infrastructure and new technologies, so our customers enjoy wider 2G, 3G and 4G coverage and vastly increased data speeds.”

The latest data reductions will complement the discounted bundle offers that will also be made available to prepaid customers in more than 2,000 less affluent suburbs and villages around the country. For qualifying communities to access further discounted voice and data deals, they need to click on the scrolling ConnectU banner on the platform via connectu.vodacom.co.za

ConnectU – which is a zero-rated platform – also went live this week. It will provide content aimed at social development and offers a variety of essential services for free. Learners and students enrolled in schools and universities can access relevant information for free, with no data costs. The ConnectU portal includes a search engine linked to open sources such as Wikipedia and Wiktionary as well as free access to job portals; free educational content on the e-School platform; free health and wellness information and free access to Facebook Flex, the low data alternative to Facebook that enables customers to stay socially connected.

Vodacom’s popular Just4You platform has been a significant contributor to the approximately 50% reduction in effective data prices over the past two years. Substantial cuts in out-of-bundle tariffs and the introduction of hourly, daily and weekly bundles with much lower effective prices have also driven increased value and affordability, resulting in R2-billion in savings for customers in 2019.

Continue Reading

Trending

Copyright © 2020 World Wide Worx