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Scientists count more than 2 million eels on one underwater mountain

Patience Seamount is an underwater mountain in Australia’s Huon Marine Park off the coast of Tasmania. Every year, it is the site of an enormous gathering of basketwork eels (Diastobranchus capensis) for reasons unknown, although most likely to spawn. The numbers are huge, but they have never been quantified.

Now a team led by marine scientist Ben Scoulding of Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO) has estimated how many are down there.

According to their study published in the journal Royal Society Open Science, the gatherings could contain as many as 2.8 million eels with a collective biomass of around 3,550 metric tons (about 3,900 U.S. tons).

Supersonic waves could explain the strange orbits of hot Jupiters and Neptunes

Using advanced new simulations, a team of astronomers in the U.S. has developed a promising new theory for how giant, gaseous exoplanets migrate into stiflingly close orbits around their host stars. Led by J. J. Zanazzi at The Pennsylvania State University, the team showed how both massive “hot Jupiters” and smaller, Neptune-sized planets could migrate from distant, elliptical orbits as they release energy via dramatic shock waves in their outer atmospheres. Their results have been published in The Astrophysical Journal.

Hot Jupiters are a class of exoplanets with masses comparable to the largest planet in our own solar system, but which orbit extremely close to their host stars—imparting them with temperatures that can exceed some 2,000 Kelvin. Not only are their orbital periods extremely short, they also cluster within a window between three and five days: a phenomenon dubbed the “hot Jupiter pileup.”

Similar clustering can also be seen in smaller gas giants, with masses between those of Neptune and Saturn, known as the “Neptune ridge.” Yet unlike hot Jupiters, these planets are strikingly scarce on orbits shorter than about three days, creating a stark observational gap named the “Neptune desert.”

The phantom lighthouse: New research explains one of Australia’s strangest illusions

There are two lighthouses on Lady Elliot Island, at the southernmost tip of Australia’s Great Barrier Reef. The first was built in 1873, but was decommissioned in 1995 when the second took over the job of warning ships off the reef. Visitors to the island, however, regularly report seeing signs of a third lighthouse. At night the beams of a nonexistent phantom lighthouse are seen far off, shining on the horizon.

This “phantom lighthouse illusion” is so well known it even gets a mention in the island’s guide for tourists. It’s not unique to Lady Elliot Island, either: the earliest known report of this phenomenon was published in 1937, and it documented the illusion off the coast of Brittany in France.

What’s going on here? One of us traveled to Lady Elliot Island to find out, then we recreated the illusion in a virtual reality environment to make sure we understood what was happening.

Ultrathin metal layer boosts spin-related signals, opening a door to ultralow-power electronics

Researchers at Kyushu University have found that an ultrathin layer of iridium manganese (IrMn) can improve two spin-related signals in a structure made of a magnetic insulator and a platinum film. By examining how spin currents are generated and absorbed, the team gained insights into how the intermediate layer improves spin transfer. The findings could inform the development of ultralow-power devices for computing and energy harvesting.

Spintronics is a more complex approach to conventional electronics that uses electron spin, in addition to electrical charge, to process and transmit information. For decades, researchers have been investigating various ways to use spin-related phenomena in computing, data storage and energy harvesting.

One such phenomenon is the spin Seebeck effect (SSE), in which a temperature difference across a magnetic material generates a spin current that can be converted into electricity. Another one is spin hall magnetoresistance (SMR), where a metal’s electrical resistance changes depending on the relative orientation of the electrical current and the magnetization of a neighboring magnetic layer. If harnessed effectively, the SSE could provide a way to recover energy from heat that would otherwise go unused, and SMR could prove useful for data storage and computing.

Atomic magnetism reveals why iron, but not chromium, can produce ammonia using sunlight

Two nearly identical materials have completely different chemical behavior. Research teams at the University of Vienna and TU Wien studied catalysts that use the energy of sunlight to produce ammonia. Surprisingly, when the three iron atoms that form tiny triangles in these catalysts are replaced by chromium atoms, the chemical reaction no longer takes place.

The teams have now explained why. Iron and chromium triangles have very different magnetic properties, and these magnetic properties also reveal whether the material works as a catalyst. The findings are published in the journal ACS Energy Letters.

Both research teams belong to the FWF Cluster of Excellence MECS (Materials for Energy Conversion and Storage), which develops new materials for the energy transition.

Microscopic springs transform fragile silicon into a flexible terahertz metamaterial

Researchers at the Osaka Research Institute of Industrial Science and Technology (ORIST), in collaboration with the University of Osaka and Tohoku University, have developed a flexible and stretchable silicon material whose response to terahertz waves can be mechanically tuned. By etching microscopic spiral springs into silicon, the team made the fragile material bendable and stretchable.

The work is published in the journal Optica.

Terahertz waves, whose frequencies lie between those of microwaves and light, hold potential for material inspection and future wireless communications. Silicon is used to fabricate low-loss optical components in terahertz bands. However, these components are rigid and can be easily broken by mechanical impact.

Explaining the difference between brittle and ductile behavior in polymer glasses

Glasses are (mostly) brittle, metals can be ductile (plastic), and liquids flow easily. Polymers are interesting because they exhibit all three types of behavior, depending on their chemical nature, temperature, and deformation rate. If polymers are not able to crystallize, their low-temperature state is glassy, and they are hard and transparent. One example is poly(methylmethacrylate) [PMMA], which has been used as an artificial glass since the early 20th century.

Surprisingly, polymer glasses can be ductile at temperatures significantly below their glass transition temperature, Tg. For a typical laboratory strain rate (~10⁻³ s⁻¹), the brittle-ductile transition temperature (BDT or TBD) can be 50–100 K below Tg. This result is surprising—naively, one would expect a “glass” to be brittle—yet polymers can deform plastically well below Tg.

Slow-motion electron camera reveals light-driven quantum jumps in graphene

Using a new slow-motion electron camera, physicists from Regensburg, Marburg and Jülich revealed how intense electric fields drive electrons in graphene, causing them to jump across energy gaps in a seemingly paradoxical manner. This was made possible by a novel combination of laser technology and electron microscopy.

The electrons’ behavior is roughly equivalent to riding an elevator where the floor indicator suddenly jumps from “1,” “2,” and “3” to “20.” You never passed through the 17 floors in between, yet you arrive on the 20th floor. What sounds like an impossible leap is actually possible in the quantum world. Such processes are called Landau-Zener-Majorana transitions. It has long been suspected that these transitions could play an increasingly important role in high-speed semiconductor electronics.

A research team from the University of Regensburg, Philipps-Universität Marburg and the Forschungszentrum Jülich has succeeded in visualizing the ultrafast dynamics of such transitions in the material graphene. The team reports on this achievement in its latest study, published in the journal Nature.

When simulations fall short, this spectrometer learns for itself

An NMR spectrometer can reveal molecular structure down to the atomic level, but weak signals limit what it can see. Now, Aarhus University researchers have used AI to let the spectrometer learn the best pulse sequence directly from the sample.

Imagine trying to shepherd a group of sugar-fueled children through an amusement park. You cannot work out in advance exactly which combination of words, tone of voice, timing and body language will keep everyone moving in the right direction. The children react differently, they influence one another, and the larger the group, the harder it becomes to predict what will work.

At some point, the best strategy is simply to try something, see what happens and adjust.

Scientists uncover new way to control magnetism and topology using light in atomically thin materials

Envision a material whose magnetic properties and electronic topology can be toggled by exposure to light, paving the way for future electronic devices that do not rely on traditional electrical switching, which wastes energy by producing heat.

Researchers at Monash University have predicted that this kind of switching is possible in the two-dimensional magnetic topological material MnBi₂Te₄, through a type of hybrid light–matter excitation they call magnetophononic polaritons. The study is published in ACS Nano.

“Controlling magnetism and topology with light has long been a challenge in topological quantum materials research. Our calculations show a way to achieve both at once, which could enable ultrafast on–off switching of topological states,” said Dr. Enamul Haque, the study’s first author, who carried out the work during his Ph.D. at Monash University.