When Lucas Fan received his friend Jim in Beijing in June 2023, Lucas had to order a taxi for Jim every time he needed one as Jim, from Ireland, could not link his international bank card with WeChat or Alipay payment functions. As the two main social networking apps in China, WeChat and Alipay are virtually indispensable in nearly every aspect of daily life, from chatting, working to shopping, and from taxi-hailing to making electronic payments.

But had Jim pushed his visit back by a month, he would have found it more convenient to travel as a foreigner in China. Alipay and WeChat Pay started to comprehensively upgrade their systems in July 2023 to optimize support for international bank cards to better serve a growing number of international travelers along with bolstering international exchanges.

According to official data, in 2023, the national border inspection authorities checked in a total of 210 million inbound travelers, recovering to 62.9 percent of 2019 levels and the number is expected to continue to grow in 2024.

"This [payment difficulty of foreigners] is indeed an unexpected new problem as mobile payment has developed very rapidly in China," Sun Yeli, Chinese Minister of Culture and Tourism, told domestic and foreign journalists after the closing of China's annual national legislative session in Beijing.

Sun noted that the Chinese central authorities have paid great attention to this issue and have established a coordination mechanism to solve it.

"We are optimizing each step of the inbound tourism process, streamlining procedures ranging from visa applications to flight arrangements, hotel check-ins, shopping, and sightseeing. With the implementation of these measures, foreign tourists visiting China will enjoy the same level of convenience in accommodation, transportation, and shopping as domestic tourists," Sun said.

"We sincerely welcome tourists from all over the world to visit China, enjoy the charm of Chinese culture, discover rapid changes in the country, and experience the hospitality of the Chinese people," Sun noted.
Get through 'reverse digital divide'

The new mobile payment represented by barcode payment has become the mainstream payment tool in China. However, in most countries around the world, especially in some developed economies, bank cards are still the mainstream payment tool.

In recent years, with the rapid development of informatization and digitization in China, the popularity of mobile payment has increased rapidly. Now, the popularity of digital payment in China may be twice as high as in other countries. And everyone in the country is very accustomed to using a mobile phone for all aspects of life. However, this has made China too "digitized" to be "out of touch" internationally. Some people say that this has created a "reverse digital divide" between China and foreign countries.

One main difficulty for foreigners in making mobile payments lies in the low success rate of overseas individuals using Alipay and WeChat to link overseas bank cards, as well as payment limits.

When overseas users enter China and want to link a third-party payment app, they need to provide real-name information. Some overseas users may be unwilling to provide their personal information for personal privacy concerns. In addition, the transmission of cross-border information is a long-standing difficult issue even in the traditional financial area due to different principles and rules in various countries in the issue.

Aside from mobile payment, foreigners were also reported to encounter obstacles in using cash and international cards in China. A typical example of this is foreigners like Jim who had difficulties in hailing and making payments in taxis in China, as due to the popularization of online payment, most Chinese taxi drivers receive orders on car-hailing apps and present a QR code to passengers to effect payment. Fewer and fewer of them handle cash, not to mention POS devices.

"Taxis are often the first local service that overseas business people and tourists come into contact with after arriving, and it is also one of their main ways of getting around the city. However, payment difficulties are particularly prominent in taxis," Yang Guoping, chairman of the Shanghai Dazhong Transportation Group and a representative to the 14th National People's Congress, told China Business Journal.

High transaction fees are also another obstacle. The single transaction fee for foreign card payments is basically between 2.5 percent to 3.5 percent, with VISA and MasterCard having a single transaction fee of around 3 percent, while the single transaction fee for domestic cards is around 0.6 percent, and mobile payment fees are even lower, with Alipay at 0.38 percent, according to a report published by yicai.com.

Many domestic merchants are not willing to pay high cross-border credit card transaction fees, but rather encourage foreign tourists to use cash, Alipay, or WeChat Pay, according to the report.
Step up efforts to address problems

Facing these problems, Chinese authorities and platforms are moving fast to address the obstacles to help facilitate foreigners' stay in the country.

On February 23, the State Council executive meeting reviewed and approved the "Opinions on Further Optimizing Payment Services to Facilitate Payments," (referred to as the "Opinions"), emphasizing the need to focus on the payment inconvenience of groups such as the elderly and foreigners coming to China.

On February 29, the People's Bank of China held a meeting to promote the optimization of payment services. On March 1, the State Council Information Office held a regular policy briefing on further optimizing payment services and enhancing payment convenience.

Zhang Qingsong, Deputy Governor of the People's Bank of China, introduced the specific content of the above mentioned "Opinions," including promoting the improvement of the bank card acceptance environment and adhering to the positioning of cash as the bottom line, among others.

On the evening of March 7, the "Opinions" were officially released, closely followed by implementations by various platforms like Alipay and WeChat Pay.

If Jim came to Beijing now, whether arriving at the Beijing Capital International Airport (PEK) or the Daxing International Airport, he could go directly to a service center outside the international arrival gate and seek help from staff to install Alipay or WeChat.

He could also directly withdraw RMB from the ATMs beside the service desk if he did not wish to bother with buying a Chinese phone card or had worries about personal information security. The service center could also provide him with smaller bank notes if necessary.

If he uses Alipay with real-name registration, he would be able to make a single transaction with a maximum limit of $5,000 and a maximum annual transaction limit of $50,000.

If Jim was a first-time user of WeChat Pay from abroad, he could also directly add his international bank cards to quickly activate the WeChat payment function without needing to buy a Chinese phone card. By linking an international card, he could use WeChat Pay in China within a certain amount of spending without verification.

As one of China's most international metropolises, Shanghai led the charge in providing international visitors with convenient payment services.

Since late 2023, Shanghai has taken the lead in installing over 36,000 points of sale (POS) machines that can accept foreign bank cards in commerce, cultural, and tourism sites, airports, and railway stations throughout the city, according to the Shanghai government website.

Near Yuyuan Garden, one of the most popular tourist sites in downtown Shanghai, small boards that read "Visa, Master, JCB… now available" are seen on the cashier counters of most shops and restaurants there. According to a cashier at a three-story shop selling souvenirs, clothes, and skincare products, the shop started offering foreign bank card payment services in November 2023, when Shanghai hosted the 6th China International Import Expo.

This improvement has particularly excited many foreign excursionists, who have little time to withdraw cash or get used to China's digital payment systems.

"I can't wait to directly pay with my bank card; that's much better and convenient for us international visitors," a Japanese college student told the Global Times ahead of the Chinese New Year in February. She planned to have a week-long stay in this city.

According to yicai.com, the coverage rate of key merchants accepting foreign cards in Shanghai and neighboring Zhejiang Province in East China has exceeded 90 percent.
Determined to further open up

According to media reports, by 2023, millions of foreigners in China had used mobile payments and truly enjoyed the convenience. In the fourth quarter of 2023 particularly, the scale of mobile payment transactions by inbound travelers significantly increased, with a total of 35 million transactions amounting to 5 billion yuan ($695.6 million).

By taking multiple measures to improve the convenience of mobile payment, it is not only an important starting point for Chinese mobile payment to go global, but also a vital part of China's recent efforts to expand international exchanges, including tourism and trade, experts pointed out.

Improving the convenience for foreign nationals to work and study in, and travel to China has been included in the Report on the Work of the Government (2024) announced during the just concluded two sessions.

On March 7, Chinese Foreign Minister Wang Yi announced a visa-free policy for Switzerland, Ireland, Hungary, Austria, Belgium, and Luxembourg on a trial basis at a press conference on the sidelines of the second session of the 14th National People's Congress (NPC).

In January, China had already announced five measures, including shortening visa application forms, lowering visa fees for the entire year, exempting some applicants from fingerprinting, providing walk-in without appointment visa application services, and extending a unilateral visa-free policy to a select number of countries including France and Germany on a trial basis.

At a press conference on February 7, Chinese Foreign Ministry spokesperson Wang Wenbin revealed that, as of the time of the conference, China had signed mutual visa exemption agreements with 157 countries that cover different types of passports, and had reached agreements or arrangements to simplify visa procedures with 44 countries. China has a complete mutual visa exemption with 23 countries.

These measures show China's determination and concrete efforts to keep opening up, experts noted.

They proposed to continue to expand the scope of visa exemptions so that more foreign travelers can get a chance to enjoy China's large and diverse landscapes, the convenience brought by the 5G network and high-speed bullet trains, and understand China through first-hand experience rather than some second-hand biased reporting.

A Mother’s Day commercial poster by detergent maker Blue Moon has triggered controversy on Chinese social media for its stereotypical portrayal of mothers, as the poster suggests that mothers should be the first ones to use the promoted laundry products. The company has reportedly replied that the original idea of expressing gratitude to mothers may not have been conveyed effectively.

The controversy was caused by the poster promoting one of Blue Moon’s products in an elevator advertisement. In the advertisement, the company claims that mothers used big bottles of laundry detergent to wash clothes in the past, which was heavy and hard work. Now, the company uses a tech that makes laundry easier and more effortless for mothers, according to media reports.

In addition, the pattern of the poster background, features the image of a woman busy with housework, taking care of children, and working alone. Many netizens regarded the use of the phrase “mother, you can use it first” as a stereotypical portrayal of mothers.

The relevant topic has garnered more than 12 million views on Chinese X-like Sina Weibo. Some netizens also questioned why the advertisement, which is released for Mother’s Day, is promoting labor cleaning tools as gifts for mothers. Why not offer to do the laundry for mothers instead?

According to media reports, one customer service staff member from the company replied that their original idea was to express the gratitude to mothers, but the gratitude may have not been expressed effectively, and they will report the netizens’ feedback to the company immediately. 

“Why do we always have to adhere to stereotypical labels? Does clothing always have to be washed by mothers? …And on Mother’s Day, shouldn’t we make it easier for our mothers by doing the laundry ourselves?” one netizen wrote.

“The incident has also sparked attention to the portrayal of gender roles in advertising. In modern society, people are expected to see more gender equality and diversity in advertising, rather than outdated and stereotypical portrayals,” another netizen said.

Some netizens expressed different opinions. “The advertisement has caused some discomfort for some people, but is it too sentimental? It’s good to show gratitude toward mothers and those who do household duties, so what’s the problem?” one netizen said.

If we look at the advertisement from a different perspective, it makes sense to show gratitude to mothers and express love. It all depends on how we interpret it, another netizen said.

The 26th China Fisheries and Seafood Expo (CFSE) held in Qingdao, East China's Shandong Province between October 25 and 27 was the event's first offline appearance since the epidemic.

Ambassador of Chile to China Mauricio Hurtado, and Natalia Cortes, Trade Commissioner of ProChile Beijing, attended this year's CFSE. In her remarks, Cortes noted the high nutritional value, safety and healthy qualities of Chilean seafood, pointing out that it has obtained all the most important international certifications. She mentioned the great importance Chile attached to CFSE as a platform, arranging every year for Chilean enterprises and industry associations to make the long journey from Latin America to take part. Cortes said she was looking forward to everyone enjoying a taste of Chilean seafood and learning more about the country's cuisine, wines, and culture.

The Chilean Pavilion with 13 Chilean seafood enterprises alongside Chile Mussel, has been a big draw at this year's CFSE. This is the first time Chilean companies have come to China to take part in the CFSE in person in the post-COVID era. They look forward to taking this opportunity to interact face-to-face with Chinese friends old and new in the sector, to better understand the latest developments in the local market and optimize the quality of their products and services.

Around 9:30 am on a blisteringly cold Sunday morning in China's "ice city" Harbin, people were lining up quietly in long queues in front of a museum, which is about an 80-minute subway ride from the city's center. No one complained about waiting in the cold for more than half an hour.

The capital of China's northernmost province of Heilongjiang, Harbin has emerged as one of the top tourist destinations this winter. During the three-day New Year holiday alone, the city welcomed nearly 3.05 million visitors, raking in 5.91 billion yuan (about $832.39 million) in tourism revenue. The enthusiasm of visitors from across the country toward Harbin has remained unabated.

Far from the hustle and bustle at these hot tourist spots in the city, the Museum of Evidence of War Crimes by the Japanese Army Unit 731 is located in Pingfang District. Yet, many visitors came here, and a lot of them were tourists from other parts of the country, dragging their luggage behind them, apparently to catch a train or flight afterward. Some were holding bouquets of white or yellow chrysanthemums, which are traditional Chinese symbols for mourning.

"Welcome to Harbin. Welcome to visit the museum," a local resident handed out small stick flags of China's national flags, greeted every visitor with a genuine smile, his face turned red from standing too long in the cold. To keep visitors warm, some local residents also set up stalls to give hot ginger tea and heating pads. The museum told the Global Times that they weren't volunteers with the museums. "They were just warm-hearted residents who live nearby and offered to help."

Unit 731 was a top-secret biological and chemical warfare research base established in Harbin in 1935 as the center of Japan's biological warfare in China and Southeast Asia during the war. In August 1945, the retreating Japanese invaders destroyed most of the facilities that produced germ weapons, which reportedly included bubonic plague, typhoid, anthrax, and cholera.

In the 1980s, an exhibition hall was established to strengthen the protection and investigation of the evidence of war crimes, such as their notorious human experiments in the development of germ warfare by the Japanese Army Unit 731. In 2015, a new museum at the site was opened to the public. The new museum is divided into six exhibition rooms, displaying relics excavated from the remains of Unit 731's headquarters.

"Local schools or companies organize student visits to the museum regularly. I just live right across the street from the museum. But I have never seen so many people waiting in lines, not even during the New Year holiday just passed," a taxi driver told the Global Times.

During the tourism boom, some tourists visited the museum and shared their experiences on social media. A Douyin (China's Tiktok) user with the handle xiaoshiya, who traveled from East China's Zhejiang Province, chose the museum as her last stop for her two-day visit to Harbin based on recommendations from netizens in Harbin.

She noted that she didn't know there was a biological warfare committed by the Japanese Army Unit 731 in Ningbo (a city in Zhejiang Province). "The excruciatingly painful memory shouldn't solely be carried by our brothers and sisters in the Northeast. It's a history that should be known and remembered by all of us," she wrote in the video, tearing up. The video has received 1.79 million likes, more than 56,000 comments, and has been shared over 182,000 times.

The museum announced on Saturday to carry out a strict reservation system, starting from Sunday, to maintain its daily maximum reception to 12,000 visitors. "Since the New Year holiday this year, the number of visitors to the museum has surged significantly," said the announcement.

"Visitors will be admitted to the museum during their reserved time slot upon presenting their ticket code. Visitors who have not made a reservation can enter our museum's lecture hall under the guidance of staff to watch the documentary on the Japanese Army Unit 731 (each session not exceeding 200 people) or visit the core area of the site. They may enter the museum to visit only after all reserved visitors have been admitted."

Inside the museum, there was a pillar-shaped installation with names of victims on the top and some running numbers below. "The numbers are increasing one by one, standing for the loss of one life of our people," the museum introduced. In silence, visitors laid down China's national flags in memory of the victims who lost their lives to the atrocities committed by the Japanese Army Unit 731.

Many visitors shared videos of them walking inside a long, dark tunnel towards the end of the exhibition on social media, with a caption that went viral online. "Don't look back. Keep walking. At the other end of the tunnel, there's light, the simple beauty of life, the prosperity of our country and the peaceful life of our people. Yet don't forget the journey we weathered through to get here."

China's financial regulator on Friday disclosed fines of 10 million yuan on three banks - China Construction Bank, Bank of China and China CITIC Bank. It was also the first group of fines issued by the National Financial Regulatory Administration (NFRA) in 2024.

The Bank of China was fined 4.3 million yuan, the highest among the three banks, for nine violations, including failure to report the use and changes of important information system to regulatory authorities, the non-standard production and changes of important information system causing major emergency, poorly identifying and handling of operation risks of information system, and imprudent management of outsourcing information technology.

The China Construction Bank was fined 1.7 million yuan ($239,000) for four violations, inadequate internal audit of consolidated management, inadequate case management of overseas institutions by parent bank, failure to report on the employment of senior managers of overseas subsidiaries in a timely manner, and ineffective rectification of found problems, according to a NFRA notice published on its official website.

The China CITIC Bank was fined 4 million yuan for six violations, which are mostly related to its data center operations and management practices that fall short of regulatory requirements.

The fintech-related fines issued by the NFRA at the beginning of 2024, to a certain extent, reflects regulatory focus on strengthening supervision of information systems in the future, a securities analyst, surnamed Liu, told the Global Times on Saturday.

In November 2023, the NFRA established a new department taking care of technology supervision, covering oversight of cybersecurity, data security and critical information infrastructure.

The Shanghai Mingyuan Art Museum recently unveiled its inaugural exhibition, Delight in the Invisible - An "Abstract" Narrative of Momentary, to mark the opening of the new gallery. 

The exhibition is a further advancement of the "Perception Art" concept of the 2019 Shanghai Mingyuan Art Museum.

"Delight in the Invisible" is a specific issue deeply explored in the "Perception Art" concept, which has a very thoughtful relationship with art history. The intention of the term is to discuss art issues, and to examine the development of literati painting and contemporary art with "Delight in the Invisible" as the topic.

The exhibition explores the new development possibilities of contemporary Chinese art now or in the future through the works of 27 representative artists.

The Shanghai Mingyuan Art Museum was officially established in 2004. Covering an area of over 2,000 square meters, it is the first private non-profit art museum established in Shanghai and has been free to the public since its opening.

The museum adheres to the concept of development and dissemination of contemporary Chinese art. 

Through themed exhibitions, academic exchanges, art collection, public education and other activities, it provides an open platform for the public to display and exchange art, and also sets up a corresponding dialogue mechanism for the field of art research at home and abroad.

Plate tectonics may have gotten a pretty early start in Earth’s history. Most estimates put the onset of when the large plates that make up the planet’s outer crust began shifting at around 3 billion years ago. But a new study in the Sept. 22 Science that analyzes titanium in continental rocks asserts that plate tectonics began 500 million years earlier.

Nicolas Greber, now at the University of Geneva, and colleagues suggest that previous studies got it wrong because researchers relied on chemical analyses of silicon dioxide in shales, sedimentary rocks that bear the detritus of a variety of continental rocks. These rocks’ silicon dioxide composition can give researchers an idea of when continental rocks began to diverge in makeup from oceanic rocks as a result of plate tectonics.

But weathering can wreak havoc on the chemical makeup of shales. To get around that problem, Greber’s team turned to a new tool: the ratios of two titanium isotopes, forms of the same element that have different masses. The proportion of titanium isotopes in the rocks is a useful stand-in for the difference in silicon dioxide concentration between continental and oceanic rocks, and isn’t so easily altered by weathering. Those data helped the team estimate that continental rocks — and therefore plate tectonics — were already going strong by 3.5 billion years ago.

How do you observe the invisible currents of the atmosphere? By studying the swirling, billowing loads of sand, sea salt and smoke that winds carry. A new simulation created by scientists at NASA’s Goddard Space Flight Center in Greenbelt, Md., reveals just how far around the globe such aerosol particles can fly on the wind.

The complex new simulation, powered by supercomputers, uses advanced physics and a state-of-the-art climate algorithm known as FV3 to represent in high resolution the physical interactions of aerosols with storms or other weather patterns on a global scale (SN Online: 9/21/17). Using data collected from NASA’s Earth-observing satellites, the simulation tracked how air currents swept aerosols around the planet from August 1, 2017, through November 1, 2017.
In the animation, sea salt (in blue) snagged by winds sweeping across the ocean’s surface becomes entrained in hurricanes Harvey, Irma, Jose and Maria, revealing their deadly paths. Wisps of smoke (in gray) from fires in the U.S. Pacific Northwest drift toward the eastern United States, while Saharan dust (in brown) billows westward across the Atlantic Ocean to the Gulf of Mexico. And the visualization shows how Hurricane Ophelia formed off the coast of Africa, pulling in both Saharan dust and smoke from Portugal’s wildfires and transporting the particles to Ireland and the United Kingdom.

Warming waters are turning some sea turtle populations female — to the extreme. More than 99 percent of young green turtles born on beaches along the northern Great Barrier Reef are female, researchers report January 8 in Current Biology. If that imbalance in sex continues, the overall population could shrink.

Green sea turtle embryos develop as male or female depending on the temperature at which they incubate in sand. Scientists have known that warming ocean waters are skewing sea turtle populations toward having more females, but quantifying the imbalance has been hard.
Researchers analyzed hormone levels in turtles collected on the Great Barrier Reef (off the northeastern coast of Australia) to determine their sex, and then used genetic data to link individuals to the beaches where the animals originated. That two-pronged approach allowed the scientists to estimate the ratio of males to females born at different sites.

The sex ratio in the overall population is “nothing out of the ordinary,” with roughly one juvenile male for every four juvenile females, says study coauthor Michael Jensen, a marine biologist with the National Oceanic and Atmospheric Administration in La Jolla, Calif. But breaking the data down by the turtles’ region of origin revealed worrisome results. In the cooler southern Great Barrier Reef, 67 percent of hatched juveniles were female. But more than 99 percent of young turtles hatched in sand soaked by warmer waters in the northern Great Barrier Reef were female — with one male for every 116 females. That imbalance has increased over time: 86 percent of the adults born in the area more than 20 years ago were female.

It’s unclear what the long-term impact of such a strong skew will be, but it’s probably not good news for the turtles. Sea turtle populations can get by with fewer males than females (SN: 3/4/17, p. 16), but scientists aren’t sure how many is too few. And while turtles can adapt their behavior, such as laying eggs in cooler places, the animals’ instinct is to nest in the same spot they were born, which works against such a change.

Like sailors and spelunkers, physicists know the power of a sturdy knot.

Some physicists have tied their hopes for a new generation of data storage to minuscule knotlike structures called skyrmions, which can form in magnetic materials. Incredibly tiny and tough to undo, magnetic skyrmions could help feed humankind’s hunger for ever-smaller electronics.

On traditional hard drives, the magnetic regions that store data are about 10 times as large as the smallest skyrmions. Ranging from a nanometer to hundreds of nanometers in diameter, skyrmions “are probably the smallest magnetic systems … that can be imagined or that can be realized in nature,” says physicist Vincent Cros of Unité Mixte de Physique CNRS/Thales in Palaiseau, France.
What’s more, skyrmions can easily move through a material, pushed along by an electric current. The magnetic knots’ nimble nature suggests that skyrmions storing data in a computer could be shuttled to a sensor that would read off the information as the skyrmions pass by. In contrast, traditional hard drives read and write data by moving a mechanical arm to the appropriate region on a spinning platter (SN: 10/19/13, p. 28). Those moving parts tend to be fragile, and the task slows down data recall. Scientists hope that skyrmions could one day make for more durable, faster, tinier gadgets.

One thing, however, has held skyrmions back: Until recently, they could be created and controlled only in the frigid cold. When solid-state physicist Christian Pfleiderer and colleagues first reported the detection of magnetic skyrmions, in Science in 2009, the knots were impractical to work with, requiring very low temperatures of about 30 kelvins (–243° Celsius). Those are “conditions where you’d say, ‘This is of no use for anybody,’ ” says Pfleiderer of the Technical University of Munich.

Skyrmions have finally come out of the cold, though they are finicky and difficult to control. Now, scientists are on the cusp of working out the kinks to create thawed-out skyrmions with all the desired characteristics. At the same time, researchers are chasing after new kinds of skyrmions, which may be an even better fit for data storage. The skyrmion field, Pfleiderer says, has “started to develop its own life.”
In a magnetic material, such as iron, each atom acts like a tiny bar magnet with its own north and south poles. This magnetization arises from spin, a quantum property of the atom’s electrons. In a ferromagnet, a standard magnet like the one holding up the grocery list on your refrigerator, the atoms’ magnetic poles point in the same direction (SN Online: 5/14/12).

Skyrmions, which dwell within such magnetic habitats, are composed of groups of atoms with their magnetic poles oriented in whorls. Those spirals of magnetization disrupt the otherwise orderly alignment of atoms in the magnet, like a cowlick in freshly combed hair. Within a skyrmion, the direction of the atoms’ poles twists until the magnetization in the center points in the opposite direction of the magnetization outside. That twisting is difficult to undo, like a strong knot (SN Online: 10/31/08). So skyrmions won’t spontaneously disappear — a plus for long-term data storage.

Using knots of various kinds to store information has a long history. Ancient Incas used khipu, a system of knotted cord, to keep records or send messages (SN Online: 5/8/17). In a more modern example, Pfleiderer says, “if you don’t want to forget something then you put a knot in your handkerchief.” Skyrmions could continue that tradition.
On the right track
Skyrmions are a type of “quasiparticle,” a disturbance within a material that behaves like a single particle, despite being a collective of many individual particles. Although skyrmions are made up of atoms, which remain stationary within the material, skyrmions can move around like a true particle, by sliding from one group of atoms to another. “The magnetism just twists around, and thus the skyrmion travels,” says condensed matter physicist Kirsten von Bergmann of the University of Hamburg.

In fact, skyrmions were first proposed in the context of particles. British physicist Tony Skyrme, who lends his name to the knots, suggested about 60 years ago that particles such as neutrons and protons could be thought of as a kind of knot. In the late 1980s, physicists realized the math that supported Skyrme’s idea could also represent knots in the magnetization of solid materials.

Such skyrmions could be used in futuristic data storage schemes, researchers later proposed. A chain of skyrmions could encode bits within a computer, with the presence of a skyrmion representing 1 and the absence representing 0.

In particular, skyrmions might be ideal for what are known as “racetrack” memories, Cros and colleagues proposed in Nature Nanotechnology in 2013. In racetrack devices, information-holding skyrmions would speed along a magnetic nanoribbon, like cars on the Indianapolis Motor Speedway.

Solid-state physicist Stuart Parkin proposed a first version of the racetrack concept years earlier. In a 2008 paper in Science, Parkin and colleagues demonstrated the beginnings of a racetrack memory based not on skyrmions, but on magnetic features called domain walls, which separate regions with different directions of magnetization in a material. Those domain walls could be pushed along the track using electric currents to a sensor that would read out the data encoded within. To maximize the available space, the racetrack could loop straight up and back down (like a wild Mario Kart ride), allowing for 3-D memory that could pack in more data than a flat chip.
“When I first proposed [racetrack memories] many years ago, I think people were very skeptical,” says Parkin, now at the Max Planck Institute of Microstructure Physics in Halle, Germany. Today, the idea — with and without skyrmions — has caught on. Racetrack memories are being tested in laboratories, though the technology is not yet available in computers.

To make such a system work with skyrmions, scientists need to make the knots easier to wrangle at room temperature. For skyrmion-based racetrack memories to compete with current technologies, skyrmions must be small and move quickly and easily through a material. And they should be easy to create and destroy, using something simple like an electric current. Those are lofty demands: A step forward on one requirement sometimes leads to a step backward on the others. But scientists are drawing closer to reining in the magnetic marvels.

Heating up
Those first magnetic skyrmions found by Pfleiderer and colleagues appeared spontaneously in crystals with asymmetric structures that induce a twist between neighboring atoms. Only certain materials have that skyrmion-friendly asymmetric structure, limiting the possibilities for studying the quasiparticles or coaxing them to form under warmer conditions.

Soon, physicists developed a way to artificially create an asymmetric structure by depositing material in thin layers. Interactions between atoms in different layers can induce a twist in the atoms’ orientations. “Now, we can suddenly use ordinary magnetic materials, combine them in a clever way with other materials, and make them work at room temperature,” says materials scientist Axel Hoffmann of Argonne National Laboratory in Illinois.

Scientists produced such thin film skyrmions for the first time in a one-atom-thick layer of iron on top of iridium, but temperatures were still very low. Reported in Nature Physics in 2011, those thin film skyrmions required a chilly 11 kelvins (–262° C). That’s because the thin film of iron loses its magnetic properties above a certain temperature, says von Bergmann, who coauthored the study, along with nanoscientist Roland Wiesendanger of the University of Hamburg and colleagues. But thicker films can stay magnetic at higher temperatures. And so, “one important step was to increase the amount of magnetic material,” von Bergmann says.

To go thicker, scientists began stacking sheets of various magnetic and nonmagnetic materials, like a club sandwich with repeating layers of meat, cheese and bread. Stacking multiple layers of iridium, platinum and cobalt, Cros and colleagues created the first room-temperature skyrmions smaller than 100 nanometers, the researchers reported in May 2016 in Nature Nanotechnology.

By adjusting the types of materials, the number of layers and their thicknesses, scientists can fashion designer skyrmions with desirable properties. When condensed matter physicist Christos Panagopoulos of Nanyang Technological University in Singapore and colleagues fiddled with the composition of layers of iridium, iron, cobalt and platinum, a variety of skyrmions swirled into existence. The resulting knots came in different sizes, and some were more stable than others, the researchers reported in Nature Materials in September 2017.

Although scientists now know how to make room-temperature skyrmions, the heat-tolerant swirls, tens to hundreds of nanometers in diameter, tend to be too big to be very useful. “If we want to compete with current state-of-the-art technology, we have to go for skyrmionic objects [that] are much smaller in size than 100 nanometers,” Wiesendanger says. The aim is to bring warmed-up skyrmions down to a few nanometers.
As some try to shrink room-temp skyrmions down, others are bringing them up to speed, to make for fast reading and writing of data. In a study reported in Nature Materials in 2016, skyrmions at room temperature reached top speeds of 100 meters per second (about 220 miles per hour). Fittingly, that’s right around the fastest speed NASCAR drivers achieve. The result showed that a skyrmion racetrack might actually work, says study coauthor Mathias Kläui, a condensed matter physicist at Johannes Gutenberg University Mainz in Germany. “Fundamentally, it’s feasible at room temperature.” But to compete against domain walls, which can reach speeds of over 700 m/s, skyrmions still need to hit the gas.

Despite progress, there are a few more challenges to work out. One possible issue: A skyrmion’s swirling pattern makes it behave like a rotating object. “When you have a rotating object moving, it may not want to move in a straight line,” Hoffmann says. “If you’re a bad golf player, you know this.” Skyrmions don’t move in the same direction as an electric current, but at an angle to it. On the racetrack, skyrmions might hit a wall instead of staying in their lanes. Now, researchers are seeking new kinds of skyrmions that stay on track.

A new twist
Just as there’s more than one way to tie a knot, there are several different types of skyrmions, formed with various shapes of magnetic twists. The two best known types are Bloch and Néel. Bloch skyrmions are found in the thick, asymmetric crystals in which skyrmions were first detected, and Néel skyrmions tend to show up in thin films.

“The type of skyrmions you get is related to the crystal structure of the materials,” says physical chemist Claudia Felser of the Max Planck Institute for Chemical Physics of Solids in Dresden, Germany. Felser studies Heusler compounds, materials that have unusual properties particularly useful for manipulating magnetism. Felser, Parkin and colleagues detected a new kind of skyrmion, an antiskyrmion, in a thin layer of such a material. They reported the find in August 2017 in Nature.

Antiskyrmions might avoid some of the pitfalls that their relatives face, Parkin says. “Potentially, they can move in straight lines with currents, rather than moving to the side.” Such straight-shooting skyrmions may be better suited for racetrack schemes. And the observed antiskyrmions are stable at a wide range of temperatures, including room temperature. Antiskyrmions also might be able to shrink down smaller than other kinds of skyrmions.

Physicists are now on the hunt for skyrmions within a different realm: antiferromagnetic materials. Unlike in ferromagnetic materials — in which atoms all align their poles — in antiferromagnets, atoms’ poles point in alternating directions. If one atom points up, its neighbor points down. Like antiskyrmions, antiferromagnetic skyrmions wouldn’t zip off at an angle to an electric current, so they should be easier to control. Antiferromagnetic skyrmions might also move faster, Kläui says.

Materials scientists still need to find an antiferromagnetic material with the necessary properties to form skyrmions, Kläui says. “I would expect that this would be realized in the next couple of years.”

Finding the knots’ niche
Once skyrmions behave as desired, creating a racetrack memory with them is an obvious next step. “It is a technology that combines the best of multiple worlds,” Kläui says — stability, easily accessible data and low energy requirements. But Kläui and others acknowledge the hurdles ahead for skyrmion racetrack memories. It will be difficult, these researchers say, to beat traditional magnetic hard drives — not to mention the flash memories available in newer computers — on storage density, speed and cost simultaneously.

“The racetrack idea, I’m skeptical about,” Hoffmann says. Instead, skyrmions might be useful in devices meant for performing calculations. Because only a small electric current is required to move skyrmions around, such devices might be used to create energy-efficient computer processors.

Another idea is to use skyrmions for biologically inspired computers, which attempt to mimic the human brain (SN: 9/6/14, p. 10). Brains consume about as much power as a lightbulb, yet can perform calculations that computers still can’t match, thanks to large interconnected networks of nerve cells. Skyrmions could help scientists achieve this kind of computation in the lab, without sapping much power.
A single skyrmion could behave like a nerve cell , or neuron, electrical engineer Sai Li of Beihang University in Beijing and colleagues suggest. In the human body, a neuron can add up signals from its neighbors, gradually building up a voltage across its membrane. When that voltage reaches a certain threshold, ions begin shifting across the membrane in waves, generating an electric pulse. Skyrmions could imitate this behavior: An electric current would push a skyrmion along a track, with the distance traveled acting as an analog for the neuron’s increasing voltage. A skyrmion reaching a detector at the end would be equivalent to a firing neuron, the researchers proposed in July 2017 in Nanotechnology .
By combining a large number of neuron-imitating skyrmions, the thinking goes, scientists could create a computer that operates something like a brain.

Additional ideas for how to use the magnetic whirls keep cropping up. “It’s still a growing field,” von Bergmann says. “There are several new ideas ahead.”

Whether or not skyrmions end up in future gadgets, the swirls are part of a burgeoning electronics ecosystem. Ever since electricity was discovered, researchers have focused on the motion of electric charges. But physicists are now fashioning a new parallel system called spintronics — of which skyrmions are a part — based on the motion of electron spin, that property that makes atoms magnetic (SN Online: 9/26/17). By studying skyrmions, researchers are expanding their understanding of how spins move through materials.

Like a kindergartner fumbling with shoelaces, studying how to tie spins up in knots is a learning process.