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Category: nanotechnology

Silver nanoparticles enable assembly of a theorized, previously unobserved crystal metallic structure

Using finely tuned nanoscale building blocks, researchers from Brown University and the University of Michigan College of Engineering have stabilized a fleeting structural phase of matter that had been predicted theoretically but never before stabilized in a physical material.

The new nanoparticle superlattice, described in the journal Science, freezes an elusive intermediate state between two of nature’s most common crystal metallic arrangements. Beyond describing new details about how this transition works, the new structure exhibits extraordinary optical properties that could be useful in quantum computing or other quantum information systems.

More broadly, the work provides a new recipe for using custom-shaped nanoparticles to engineer entirely new classes of materials with tailored properties.

Ultrafast holographic imaging reveals electron and magnetic dynamics inside next-generation materials

An extremely fast microscopy method to research the interaction of light and matter makes it possible to study optical processes on very short timescales. To this end, a German–Italian research team is combining holographic imaging with ultrafast spectroscopy in an innovative way. In this manner, even extremely short-lived electronic and magnetic phenomena—which play a major role in the development and application of novel energy materials—can be observed.

The research was conducted as part of an international collaboration between scientists from the Institute for Physical Chemistry at Heidelberg University, the Polytechnic University of Milan, and the Institute for Photonics and Nanotechnologies in Milan (Italy). The findings are published in the journal Nature Photonics.

At the heart of the research is a pump-probe microscope, which is used to conduct so-called excitation and detection experiments. In this process, the material under investigation is first excited by a short light pulse, while a second pulse records the time-dependent response. By comparing measurements taken with the excitation on and off, these processes can be accurately reconstructed.

Electrical ‘knob’ can switch light on, off and tune intensity at the nanoscale

Physicists from Emory University have led work to develop a microscopic, nonlinear light source that can be switched on, off or tuned to a particular intensity by an electrical “knob.” The paper is published in the journal Optica, and could aid in the design of smaller, more flexible technologies for communications, sensing and quantum computing.

The new method focuses on a type of nonlinear optics known as second harmonic generation (SHG), where two photons of the same frequency interact with a material and combine into a single photon with twice the frequency.

“Nobody had previously shown that you can tune second harmonic generation with an electric knob in such a small device,” says Hayk Harutyunyan, senior author of the paper and Emory professor of physics.

Metamaterials enable control of heat transfer at nanoscale, potentially transforming energy and electronics

Heat behaves in predictable ways: a hot cup of coffee cools, a laptop warms your hands, the sun heats Earth. But at scales thousands of times smaller than a human hair, those rules begin to break down, and scientists are learning how to take advantage of that.

A new study, published in Nature from researchers at Carnegie Mellon University, in collaboration with Stanford University and Purdue University, shows that heat can be manipulated far more powerfully than previously demonstrated using carefully engineered metamaterials. The work offers one of the clearest experimental confirmations yet that heat transfer can be actively designed and enhanced.

At the core of the discovery is a phenomenon called near-field radiative heat transfer. When two objects are brought extremely close together—just a few hundred nanometers apart—heat doesn’t simply radiate away in the usual sense. Instead, it can tunnel across the gap through electromagnetic waves, dramatically increasing how much energy flows between them.

Memory-preserving transistors could bypass the Boltzmann limit

Researchers have created a new theoretical framework that shows how memory-preserving “memtransistors” could overcome the intrinsic limits in efficiency faced by conventional semiconductor transistors, imposed by the laws of thermodynamics.

Led by Victor Lopez-Richard at the Federal University of São Carlos, Brazil, in collaboration with the University of Wurzburg, in Germany, and the University of Richmond, U.S., the researchers showed that further improvements to transistor switching efficiency could be reached simply by harnessing memory effects that are already present in many nanoscale devices. The research has been published in Physical Review Applied.

Prof. RHO Jun-seok Advances Metalens Technology from Manufacturing to Display Applications in Two Nature Papers

Nanoprinting imprinting metalenses 100x faster than lithography.

Professor RHO Jun-seok from the Departments of Mechanical Engineering and Chemical Engineering at POSTECH has gained international attention for developing a mass-production process for metalenses and a switchable 2D-3D display technology based on them. The two studies were simultaneously published in the April 30 issue of Nature. This marks the first case in Korea of a researcher publishing two separate papers as corresponding author in the same issue of the journal.

A metalens is a flat optical device that controls light using nanoscale structures rather than curved glass. By replacing bulky glass lenses with engineered surface patterns, optical systems become far thinner and lighter. Because this enables control of light at scales smaller than its wavelength, metamaterials are often regarded as a Nobel Prize–worthy field of research.

The first study addressed a key barrier to commercialization: large-scale manufacturing. Production has so far relied on expensive and complex semiconductor fabrication processes due to the extreme precision required, making it slow, costly, and largely limited to laboratory research. To overcome this, Prof. RHO’s team developed a Roll-to-Roll Nanoimprint process enabling continuous production using a cylindrical roller. Instead of fabricating nanoscale structures one by one on rigid molds, flexible polymer molds were used to imprint patterns onto thin films. This shifts fabrication from a one-at-a-time process to continuous factory-scale production. The team produced over 300 metalenses per second, about 100 times faster than conventional methods, while maintaining consistent performance over a 200-meter process.

Low-power, flexible radio-frequency transistors break 100 GHz barrier

Over the past decades, electronics engineers worldwide have been trying to develop devices that could enable even faster communications between devices, all while consuming less energy. To meet the demands of the sixth generation (6G) of wireless communication technology, these devices should operate at frequencies above 100 gigahertz (GHz).

So far, developing flexible electronic components that can operate at these high frequencies while consuming little power has proved challenging. One promising approach for fabricating these devices entails the use of carbon nanotubes (CNTs), extremely thin and cylindrical structures with advantageous electrical and thermal properties.

Researchers at Peking University and Stanford University recently developed new flexible and low-power CNT-based transistors that operate at frequencies above 100 GHz. These transistors, presented in a paper published in Nature Electronics, could potentially help to speed up communications between future smartphones, sensors, wearable devices, and other flexible devices.

Single-step 8-9x expansion reveals nanoscale centrioles without electron microscopy

In a study published in ACS Nano, researchers from National Taiwan University report a new expansion microscopy strategy termed high-fold homogeneous expansion microscopy (hiHomoExM), capable of achieving approximately 8–9× isotropic expansion in a single expansion step while preserving delicate ultrastructural organization.

Expansion microscopy works by embedding biological samples within a swellable polymer hydrogel. Following chemical processing, the hydrogel expands uniformly in water, physically separating biomolecules and effectively increasing the spatial resolution achievable by conventional light microscopes.

“To achieve nanoscale imaging faithfully, both high expansion and homogeneous specimen preservation are essential,” explains the research team. “Nonuniform expansion can distort ultrastructural information and limit biological interpretation.”

Teaching thermodynamic laws to AI unlocks a polymer modeling challenge

For more than half a century, materials scientists have struggled with how to simulate the complexity of polymer materials. An individual chain can comprise tens of thousands of atoms, a melt or composite contains billions, and the properties engineers actually care about, such as how an adhesive grips a surface, how a self-assembling block copolymer locks into a nanostructure, or how a biopolymer film stretches without tearing, emerge only over length and time scales that forcible atomistic simulation cannot reach.

The standard workaround is coarse-graining: replacing groups of atoms with simpler mesoscopic particles so the model is fast enough to run. The catch is that this compression almost always sacrifices physics. Conventional coarse-grained polymer models can usually reproduce equilibrium structure or large-scale dynamics, but rarely both, and they routinely fail to capture the entropic and viscous forces that govern how polymers actually flow, relax, and dissipate energy. Those are the forces that dictate mechanical performance, and they are the forces that traditional machine-learning approaches, despite their flexibility, also tend to break.

A research paper recently published in Proceedings of the National Academy of Sciences introduces a new machine-learning framework that lets coarse-grained models achieve both at once. A team from Carnegie Mellon University and the University of Pennsylvania has built an AI architecture that learns coarse-grained dynamics directly from data, whether simulated or experimental, while being mathematically incapable of violating the laws of thermodynamics.

New three‑dimensional magnetic structure discovered with laser light

Flashes of femtosecond laser light, lasting just a few trillionths of a second, have made it possible to observe new magnetic structures for the first time. By using light as a remote control, researchers were able to switch magnetism into previously unseen three-dimensional states at the nanoscale.

Magnetism is often imagined as something simple, pointing in one direction or another. At very small scales, however, magnetism can behave in far more complex ways. Magnetism originates from a quantum property of electrons known as spin, which can be thought of as a tiny internal compass carried by each electron. When many spins interact inside a solid material, they can organize into stable patterns.

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