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Category: materials

Reconfigurable Ge-Si photodetector achieves ultrahigh-speed data transmission using low-loss packaging

The rapid growth of large language models is placing increasing demands on data centers, where large volumes of data must be transferred efficiently between servers. Optical interconnects are essential for enabling this communication, but as data rates continue to rise, these systems must deliver higher bandwidth while maintaining low latency and energy efficiency. However, integrating electronic and photonic components remains challenging, as conventional approaches often introduce signal loss, limit interconnect density, and restrict scalability.

As reported in Advanced Photonics Nexus, Dr. Wei Chu and colleagues have developed a reconfigurable germanium–silicon photodetector using a low-loss integration strategy based on fan-out wafer-level packaging (FOWLP). This approach enables seamless integration of electronic integrated circuits and photonic integrated circuits on a single platform without the need for traditional wire bonding, reducing parasitic loss and improving signal integrity.

The system uses a dense network of fine metal interconnects, known as a redistribution layer (RDL), to connect components with high precision. This structure supports high interconnect density—exceeding 102 connections per square millimeter—while maintaining a low insertion loss of less than 0.3 dB/mm at 100 GHz. In addition, the use of benzocyclobutene as a low-dielectric insulating material reduces transmission loss and improves thermal stability for reliable high-frequency operation.

Bilayer antiferromagnet reveals photocurrent that flips with magnetic state

In recent years, atomically thin materials—crystals only a few atoms thick—have attracted growing attention because they can exhibit physical properties that do not appear in conventional bulk materials. Among them, atomically thin magnetic materials are particularly intriguing, as they can host unconventional magnetic states and offer new possibilities for spin-based electronic technologies.

In a Nature Materials study, researchers investigated the photocurrent response of a bilayer atomically thin antiferromagnet. In this material, spins are aligned within each atomic layer, while the spin orientations of the top and bottom layers are opposite. Depending on the relative spin configuration between the two layers, the system exhibits two distinct antiferromagnetic (AFM) states.

To explore how these magnetic states interact with light, the researchers fabricated devices by attaching electrodes to bilayer samples and illuminated the center of the material, away from the electrodes. They measured both the zero-bias photocurrent and current-voltage characteristics under illumination.

Scientists Find Evidence Earth Is Drifting Through the Ashes of an Exploded Star

Earth is flying through the radioactive ashes of an ancient exploded star, and Antarctic ice preserved the evidence.

Scientists have found new evidence that Earth is moving through a cloud of ancient supernova debris left behind by a long ago stellar explosion. By examining Antarctic ice tens of thousands of years old, researchers detected iron-60, a rare radioactive isotope created when massive stars explode. The findings suggest that the Local Interstellar Cloud surrounding our Solar System contains lingering material from an ancient supernova. The study was led by an international team from the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) and published in Physical Review Letters.

Ancient Supernova Material Reaching Earth.

Garment humanoid robots, Zhejiang Humanoid lands order

Zhejiang Humanoid Robotics Innovation Center said on May 12 that it has signed a strategic partnership with Jack Technology and an order for 2,000 garment humanoid robots customized for garment manufacturing. According to Gasgoo, the company described the deal as the first mass deployment of humanoid robots in the global apparel industry. The announcement matters because garment handling combines flexible materials, tight tolerances, and repetitive production steps that have been difficult to automate with general purpose humanoids.

Garment humanoid robots face a hard manufacturing test

The source article frames apparel production as a demanding proving ground for embodied AI systems. Fabrics vary in material and shape, and they can wrinkle, shift, and deform during handling. Zhejiang Humanoid said alignment deviations for cut pieces such as collars and pockets must be kept within plus or minus 2 mm, while cutting and sewing tasks require motion precision of 0.3 to 0.5 mm.

A Solid-State Pathway to Neutrino Mass

New density-functional-theory calculations describe the radioactive decay of tritium bound to graphene, offering a way to model experiments that could open cleaner windows onto neutrino mass.

The discovery that neutrinos oscillate—shifting among three “flavors” (electron, muon, and tau) as they propagate—showed that these elusive particles must have mass. Yet their absolute mass scale and the mass ordering (whether the lightest neutrino state is predominantly electron-, muon-, or tau-like) remain unknown. Determining these properties is a central goal of modern particle physics. A promising approach involves measuring the energy spectrum of electrons emitted in nuclear decay, particularly from tritium: Because the neutrino carries away part of the decay energy, a nonzero neutrino mass slightly modifies the spectrum of emitted electrons. Precision experiments such as KATRIN have pushed this method to its limit, setting an upper bound of about 0.45 eV on the neutrino mass [1]. While KATRIN uses molecular tritium gas, new strategies aim to go further by embedding tritium in engineered materials.

Tiny forces, big effects: How particle interactions control the flow of soft materials

Sitting in a restaurant, you reach for the ketchup bottle, eyeing the basket of fries in front of you. You give the bottle a shake, then a tap. For a moment, nothing happens—the ketchup clings stubbornly to the glass. Then, all at once, it lets go and rushes out, sometimes in a steady stream, sometimes in a messy surge that threatens to flood the basket.

That awkward moment when ketchup stops behaving like a solid and suddenly starts flowing like a liquid is called “yielding.” Scientists see the same kind of behavior in many everyday and advanced materials, from toothpaste, paints and concrete to 3D-printing inks and electrodes used in next-generation batteries. Yet, what actually causes a material to hold its shape one moment and suddenly let go the next has been surprisingly hard to pin down, especially deep inside dense, opaque fluids where particle motion is difficult to see.

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