Over the past few years, engineers and material scientists have been trying to devise new optical systems in which light particles (i.e., photons) can move freely and in useful ways, irrespective of defects and imperfections. Topological phases, unique states of matter that are not defined by local properties, but by non-local and global features, can enable the robust movement of photons despite material defects.
Researchers at the University of Pennsylvania and University of California-Santa Barbara recently demonstrated the realization of Floquet Chern insulators, materials in which the periodic application of an oscillating light field or other external fields give rise to a unique topological phase, in a nonlinear photonic system. The insulators presented in their paper, which was published in Nature Nanotechnology, are based on nonlinear photonic crystals, materials with repeating patterns that can control the propagation of light and respond differently to light of different intensities.
“Topological photonics explores photonic systems that exhibit robustness against defects and disorder, enabled by protection from underlying topological phases,” wrote Jicheng Jin, Li He and their colleagues in their paper. “These phases are typically realized in linear optical systems and characterized by their intrinsic photonic band structures. We experimentally study Floquet Chern insulators in periodically driven nonlinear photonic crystals, where the topological phase is controlled by the polarization and the frequency of the driving field.”
Superconductivity is a phenomenon where certain materials can conduct electricity with zero resistance. Obviously, this has enormous technological advantages, which makes superconductivity one of the most intensely researched fields in the world.
But superconductivity is not straightforward. Take, for example, the double-dome effect. When scientists plot where superconductivity appears in material as they change how many electrons are in it, the material’s superconducting regions sometimes look like two separate “domes” on a graph.
In other words, the material becomes superconducting, then stops, then becomes superconducting again as we keep changing its electron density.
A group of scientists, including researchers from the University of Tokyo, has found evidence that liquid water once moved through the body of the asteroid that eventually gave rise to the near-Earth asteroid Ryugu. Remarkably, this activity occurred more than a billion years after the asteroid originally formed.
The discovery comes from the study of tiny rock fragments collected by the Hayabusa2 spacecraft of the Japan Aerospace Exploration Agency (JAXA). The results challenge the long-standing belief that water-related processes on asteroids happened only during the earliest stages of solar system history. This new understanding could influence models of how Earth itself was formed.
Although scientists have developed a fairly detailed picture of how the solar system came together, important questions remain. One of the biggest mysteries is how Earth acquired such an abundance of water. For decades, researchers have suspected that carbon-rich asteroids, such as Ryugu, which were created from ice and dust in the outer regions of the solar system, played a major role in supplying that water. Ryugu was visited by the Hayabusa2 mission in 2018, marking the first time a spacecraft both studied such an asteroid directly and returned samples to Earth. These precious materials are now helping researchers address some of the most fundamental questions about the origins of our planet.
Scientists have created eco-friendly “quantum inks” that can replace toxic metals in infrared detectors. The breakthrough could make night vision faster, cleaner, and more accessible to a wider range of industries.
Toxic Metals vs. Infrared Innovation
Manufacturers of infrared cameras are facing a growing challenge. Many of the materials used in today’s detectors, including toxic heavy metals, are now restricted under environmental regulations. As a result, companies often find themselves forced to choose between maintaining performance or meeting compliance standards.
Lithium-ion batteries power most electronics, but they have limited energy density—they can store only a certain amount of energy per mass or volume of the battery.
“In order to store even more energy with the same mass or volume, you will have to explore alternative energy storage technologies,” says Sai Gautam Gopalakrishnan, Assistant Professor at the Department of Materials Engineering, IISc.
Gopalakrishnan and his team have studied how to boost the movement of ions in magnesium batteries, which can have a higher energy density.
Time-varying systems, materials with properties that change over time, have opened new possibilities for the experimental manipulation of waves. Contrarily to static systems, which exhibit the same properties over time, these materials break so-called temporal translation symmetry. This in turn prompts the emergence of various fascinating phenomena, including time reflection, refraction and diffraction.
It is anticipated that within just a few decades, the surging volume of digital data will constitute one of the world’s largest energy consumers. Now, researchers at Chalmers University of Technology, Sweden, have made a breakthrough that could shift the paradigm: an atomically thin material that enables two opposing magnetic forces to coexist—dramatically reducing energy consumption in memory devices by a factor of 10.
This discovery could pave the way for a new generation of ultra-efficient, reliable memory solutions for AI, mobile technology and advanced data processing.
The article, “Coexisting Non-Trivial Van der Waals Magnetic Orders Enable Field-Free Spin-Orbit Torque Magnetization Dynamics” has been published in Advanced Materials.