High-temperature memristors enabled by interfacial engineering
TL;DR
Imagine your phone's memory chip is like a light switch. Normally, if you put that switch near a campfire, the plastic melts and it stops working. Scientists found that in regular memory chips, the metal parts essentially 'wander around' when things get extremely hot, mixing together and breaking the switch permanently. The fix? They wrapped one layer with graphene—an ultra-thin sheet of carbon atoms arranged like chicken wire. Graphene acts like a non-stick pan: the wandering metal atoms just can't get a grip and slide off instead of mixing in. With this trick, the memory switches kept working even at 700°C—hotter than molten aluminum—for billions of on-and-off cycles. It's like replacing the melting plastic switch with one made of ceramic, just by adding one atom-thin protective layer.
Non-volatile memories (NVM) that operate reliably at high temperature are essential for electronics in extreme environments. Here, we reported graphene (Gra)/HfOx/tungsten (W) memristors that operated reliably up to 700 °C with an ON/OFF current ratio >10^3, data retention >50 hours and endurance >10^9 switching cycles. Transmission electron microscopy (TEM) revealed significant W diffusion into the inert platinum (Pt) electrode of conventional Pt/HfOx/W memristors after high-temperature annealing, which was an effect responsible for the thermal failure of conventional devices but not observed in Gra/HfOx/W devices. First-principles calculations attributed the enhanced thermal stability to weaker W adsorption and higher surface diffusion barriers on graphene than metals like Pt. These results underscore the critical role of interfacial engineering and potential of 2D materials in enabling reliable high-temperature NVM technologies.
- 1Graphene/HfOx/W memristors demonstrated reliable operation up to 700 °C with an ON/OFF current ratio exceeding three orders of magnitude, data retention over 50 hours, and write endurance exceeding 10^9 switching cycles.
- 2TEM and EDS/EELS analyses revealed that W atoms diffuse through HfOx and into the Pt bottom electrode in conventional Pt/HfOx/W devices during high-temperature annealing, causing irreversible device failure, whereas no significant W diffusion was observed in graphene-based devices.
- 3First-principles calculations showed that W adatoms bind much more strongly to Pt (adsorption energy -9.08 eV) than to graphene (-2.80 eV), and W diffusion coefficients on Pt are approximately three orders of magnitude greater than on graphene, explaining graphene's superior thermal stability.
- 4The devices could be switched using 30 ns-wide voltage pulses at ~1.5 V operating voltage at 700 °C, and were successfully programmed into 32 distinct resistance states at 700 °C with Ohmic-like linearity.
- 5A 32x32 (1K) crossbar array was fabricated with a device yield of 81.25%, demonstrating the scalability and integration potential of Gra/HfOx/W memristors for high-density memory applications.
M87's black hole flipped its magnetic field
Imagine a bar magnet with a north and south pole. Now imagine that magnet suddenly flipping so north becomes south and vice versa. That's essentially what happened with the magnetic field around the giant black hole at the center of galaxy M87 — except this black hole is 6.5 billion times heavier than our Sun. Scientists noticed this flip by watching the powerful beam of energy, called a jet, that shoots out from the black hole. The direction and behavior of that beam changed in a way that revealed the magnetic field had reversed. It's a big deal because those magnetic fields are thought to act like the engine that powers and steers these cosmic jets, and we've rarely caught one flipping in action.
The 2026 World Cup's grass is an engineering problem
Imagine you're trying to play soccer in 16 different places across the United States, Canada, and Mexico — some in freezing cold, some blazing hot, some in stadiums with roofs that block sunlight. Half of those stadiums normally use fake grass. Now FIFA, the organization that runs the World Cup, wants every single pitch to feel and play exactly the same way, like a video game where every level has identical physics. To do that, they hired grass scientists — yes, that's a real job — who figured out how to grow special grass on thin mats with plastic underneath so it can be transported like a carpet, stitched with synthetic fibers so it doesn't rip when players sprint and tackle, and tested by literally shooting balls at it with a cannon to make sure it bounces right. Different grass species are used depending on whether a stadium is hot, cool, or dark. It's basically a giant, living, high-tech floor installation that has to survive the world's best athletes running on it.
Non-Mendelian inheritance of DNA methylation patterns in mice
Imagine your DNA is like a huge book of instructions. Mendel's laws are the normal rules for how chapters of that book get passed from parents to children. But there's also a layer of sticky notes on top of the book—called epigenetic marks—that tell cells which chapters to read and which to ignore. This study found that most of the time (about 93%), these sticky notes follow the normal inheritance rules. But about 7% of the time, they do something unexpected: new patterns appear that neither parent had, or a mark from one parent somehow silences the same mark from the other parent (called paramutation), or males and females end up with completely different sticky notes even when they inherit the same DNA. Scientists discovered this by using a new ultra-precise DNA reading technology in mice, and it opens the door to understanding hidden layers of how traits—and possibly diseases—are passed down through generations.
Remarks on the disproof of the unit distance conjecture
Imagine you scatter a bunch of dots on a piece of paper. The question is: how many pairs of those dots can be exactly 1 inch apart? The Erdős unit distance conjecture asked whether there's a specific mathematical formula that limits how often this can happen as you add more and more dots. Think of it like asking how many friendships can exist in a town where friends are defined as people who live exactly one mile apart — there's a suspected maximum, and Erdős guessed what that maximum should be. For decades, no one could prove or disprove his guess. Now, an AI apparently found a specific arrangement of dots (a 'counterexample') that breaks the expected limit, proving Erdős's conjecture was wrong. A team of elite mathematicians then checked and explained the AI's work in this paper.