Researchers at AMOLF, in collaboration with partners from Germany, Switzerland, and Austria, have realized a new type of metamaterial through which sound waves flow in an unprecedented fashion. It provides a novel form of amplification of mechanical vibrations, which has the potential to improve sensor technology and information processing devices.
This 2D material is only the second to exhibit the fractional quantum anomalous Hall effect, and theorists are still debating how it works.
“For the first time we have shown that even a tiny fraction of cellular material could be identified by a mass spectrometer onboard a spacecraft,” said Dr. Fabian Klenner.
How will we find life on Jupiter’s icy moon, Europa, and Saturn’s icy moon, Enceladus? This is what a recent study published in Science Advances hopes to address as a team of international researchers investigate how ice grains that are discharged from the active plumes of these small moons could possess enough organic material for life to exist. This study holds the potential to help astrobiologists develop the necessary instruments and methods to find life on these small moons, specifically with NASA’s Europa Clipper scheduled to launch this October, whose goal will be to investigate Europa’s habitability potential.
Artist’s illustration of Saturn’s moon, Enceladus, seen here upside down as the plumes are on the south pole. (Credit: NASA/JPL-Caltech)
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Weak fluctuations in superconductivity, a precursor phenomenon to superconductivity, have been successfully detected by a research group at the Tokyo Institute of Technology (Tokyo Tech). This breakthrough was achieved by measuring the thermoelectric effect in superconductors over a wide range of magnetic fields and over a wide range of temperatures, from much higher than the superconducting transition temperature to very low temperatures near absolute zero. The results of this study were published online in Nature Communications on March 16, 2024.
This revealed the full picture of fluctuations in superconductivity with respect to temperature and magnetic field, and demonstrated that the origin of the anomalous metallic state in magnetic fields—which has been an unsolved problem in the field of two-dimensional superconductivity for 30 years—is the existence of a quantum critical point, where quantum fluctuations are at their strongest.
Electrons swarm in a soup of quantum entanglement in a new class of materials called strange metals.
The unexpected observation of an aligned spin polarization in certain twisted semiconductor bilayers calls for improved models of these systems.
If you take two overlapping tiled patterns and rotate one with respect to the other, new patterns will emerge. This motif has been used in art and architecture for millennia. Over the past 15 years, materials physicists have used a similar strategy to realize new material properties. In one implementation, two material monolayers with a hexagonal atomic lattice are overlaid with an angle between the two lattices, resulting in an additional long-range lattice structure known as a moiré pattern. In 2021, scientists observed the so-called quantum anomalous Hall (QAH) effect in such a twisted bilayer, formed of MoTe2 and WSe2 monolayers [1]. Now Zui Tao at Cornell University and colleagues have used optical spectroscopy to study the interaction between these two monolayers when they are in the QAH state [2].
Loop-shaped structures called vortex rings are remarkably stable and are seen throughout nature, appearing as bubble rings blown by dolphins and smoke rings emitted by erupting volcanoes. Recently, scientists observed vortex rings made from electron spins in magnetic materials. These structures have properties that make them attractive for use in energy-efficient data storage and processing. Now Yizhou Liu and Naoto Nagaosa at the RIKEN Center for Emergent Matter Science in Japan have proposed a way to create such magnetic vortex rings on demand [1].
Liu and Nagaosa considered a nanometer-scale cylinder made of a “chiral” magnetic material, one whose magnetic structure differs from that of its mirror image. The magnetic vortex rings that form in such a system have more diverse topologies and greater stability than those that form in other systems. In numerical simulations, the researchers injected a pulse of electric current into their chiral magnetic cylinder through a circular trench etched into the cylinder’s top surface. They then studied how the current pulse affected the material’s spin configurations.
Liu and Nagaosa observed a chain of interconnected magnetic vortex rings form along the length of the cylinder. Varying the duration and amplitude of the injected current pulse, they were able to control the topology of the vortex rings and their connections. The researchers say that the next step is for experimentalists to replicate these findings in the lab. They also suggest that their technique could be adapted to produce magnetic vortex rings in other physical systems, such as liquid crystals and Bose-Einstein condensates.
Scientists from China and Japan have identified unique features of the flow field in the lower mantle. Through their study of seismic anisotropy in the upper section of the lower mantle beneath the Philippine Sea Plate, they discovered that the ancient lower mantle flow field is still preserved there.
The study was published in Nature Geoscience.
The lower mantle is an important layer of the Earth and may play an important role in the evolution and material cycling of Earth’s interior. It is generally believed to be not only the final destination of subducted slabs, but also the birthplace of mantle plumes, which are two major styles in the evolution and material cycling of the Earth’s surface and interior. However, our knowledge of the characteristics of the flow field and geodynamics of the lower mantle is still deficient.
A team of engineers led by the University of Massachusetts Amherst and including colleagues from the Massachusetts Institute of Technology (MIT) recently announced in Nature Communications that they had successfully built a tissue-like bioelectronic mesh system integrated with an array of atom-thin graphene sensors that can simultaneously measure both the electrical signal and the physical movement of cells in lab-grown human cardiac tissue.
For the past hundred years, it has been widely recognized through X-ray and electron diffraction measurements that graphene interlayers can only accommodate a single layer of alkali metal. Each layer being fully filled by single layer alkali metal atoms is considered the theoretical charging limit.
However, there have been no reports of studies directly observing the atomic arrangement of interlayer alkali metals and verifying whether graphene layers can only accommodate a single layer of alkali metal atoms or whether other techniques can achieve higher density or multiple layers of alkali metals.
The research team developed a technique to insert dense alkali metals between graphene layers. Utilizing a high-performance low-voltage (60 kV) electron microscope, they have successfully observed the arrangement structure of alkali metal atoms between the graphene layers. The alkali metals are found densely packed in a two-layer structure in both bilayer graphene and in the surface layer graphite due to the flexible extension ability of their interlayer spacing.
