strain induced superconductivity

On the lab bench lies a piece of graphite grown from gas, like a deposit on the wall of a reactor. Usually, such material is not suitable for converting heat into electricity: inside it, electrons and holes run in opposite directions and cancel each other out.

A superconductor is a material in which electricity flows without loss, like water through a perfectly smooth pipe. But if you squeeze it slightly, like a spring, its properties change. Scientists have long wanted to measure how much heat such a compressed material absorbs, but instruments couldn't fit into the cramped setup. Now they've devised a way around this obstacle.

Electricians working with high voltage are like divers: they need to see what's happening deep underwater without going down themselves. What's needed is a sensor that stays away from the dangerous current and relays information to the surface. Usually, light is used: a beam passes through a transparent crystal, and the electric field slightly rotates it.

An empty dance floor where people occasionally appear. Each moves on their own, chaotically, with no connection to the others. But when the right music starts and the hall cools down a bit, the dancers suddenly begin to form long chains and move in unison. That's roughly how electrons behave in a dilute three-dimensional gas.

A water pipe: the wider it is, the more water flows through. In superconducting contacts — Josephson junctions (bridges through which current flows without resistance)—it's usually the same: the better the material conducts in its normal state, the larger the superconducting current that flows through it.

In a two-dimensional crystal of tungsten diselenide (WSe₂), light creates pairs — an electron and a hole that stick together. Such pairs are called excitons. Among them are "dark" ones: they barely emit, but they set the tone at low temperatures.

The uranium-arsenic crystal UAs2 under pressure behaves like a house with two rooms. In one room, electrons sit still; in the other, they roam freely. Under normal conditions, it's a classic "lattice Kondo" system: heavy, almost immobile electrons on 5f5/2 orbitals are surrounded by a sea of fast conduction electrons.

Usually, light does not turn an insulator into a conductor: that requires powerful laser pulses that break the material's structure. But in twisted bilayer graphene at the magic angle, things are different.

A layered cake where each tier conducts electricity differently: that's the structure of the crystal La3Ni2O7, a compound of nickel, lanthanum, and oxygen. Current flows differently along the layers than across them.

Honeycombs filled with electronic 'honey.' In the normal state, electrons move chaotically, but upon strong cooling they can pair up: this is how superconductivity emerges. The shape of these pairs, or pairing symmetry, determines the material's properties: some dance a waltz, others a foxtrot.

Electrons in a conductor are like a chaotic crowd: colliding, they lose energy, and resistance arises. In a superconductor, however, they move in unison, like partners in a well-coordinated dance, without touching each other. This state has reduced энтропией — meaning disorder. Such behavior is rare for gold and copper.

A crowd of people who can move freely but suddenly start acting as one: that's how a superconductor carries current without resistance.

When many excited atoms are gathered together, they often fire light in concert, like a crowd clapping in rhythm. This well-known phenomenon is called Dicke superradiance. But the authors of the new study asked: what happens if the atoms are not identical and each one feels its neighbors?

A bridge of aluminum just a few atoms thick is the heart of many quantum devices. Current flows through such a bridge without resistance, and it can be controlled with a magnetic field. These bridges are called Josephson junctions, after the British physicist who described their behavior.

Physicists are trying to hear a whisper in a noisy room. They build a soundproof booth, but even inside, their own breathing and heartbeat create interference. That's roughly how the search for quantum gravity goes: they want to see gravity bind two particles into a single whole — entangle them.

A quantum computer is like an orchestra where each musician is an electron spin: its tiny magnetic moment. For the orchestra to play in harmony, the conductor must hear each musician individually.

A superconductor is a material that, when strongly cooled, loses its electrical resistance: current flows through it without losses. Scientists took a layered crystal of PdTe2, similar to a stack of sheets of paper, and cooled it to temperatures below 1.8 kelvin (that's about -271°C).

Rubbing a comb against wool creates a spark. A similar principle works in triboelectric nanogenerators — devices that convert mechanical touches into electricity. The problem is that ordinary materials produce a weak charge.

A laser strikes the crystal, and it responds with flashes of light, like a bell ringing after a blow. But if the bell is warm, its sound wavers and fades. Same here: the crystal's atoms constantly jitter from heat, and this jitter disrupts the electrons' smooth flight, making the light dim and blurry.

A sheet of graphene one atom thick hangs in the air like a taut bedsheet. Heat waves, vibrations of atoms that physicists call phonons, ripple across it. Previously, it was thought that these waves quickly scatter due to strong interactions, and heat transfer is poor.

Electrons in a crystal sometimes behave like a stadium crowd doing the wave: areas of higher density alternate with nearly empty ones. This wave blocks the free flow of charges — under normal conditions, the material is not superconducting. But apply pressure, and the wave vanishes, letting electrons move without resistance.

An alloy of palladium and tellurium with a small amount of gold added behaves like a wire that loses its resistance when cooled. At ambient pressure, the three samples with different gold contents had superconducting transition temperatures of 2.7, 4.1, and 4.6 kelvin — colder than a freezer, roughly like deep space.

A barium titanate crystal is like a crowd where everyone holds a pointer. Normally, the pointers face in random directions, but when you apply an electric field, they all snap to point the same way. This ordered state is called ferroelectric: it stores information the way a compass needle stores direction.

A thin sheet of graphene, just a few micrometers thick, was placed in a weak magnetic field, and it began to push the field out of itself, like a sponge squeezing out water. This effect, known as the Meissner effect, is the hallmark of a superconductor: a material that conducts electricity without loss.

A sheet of graphene one atom thick is twisted at a small angle, and it starts behaving like a layered pie with layers slightly rotated relative to each other. At a certain twist angle, this material becomes a superconductor: electrons begin to move in pairs, like dancers in a waltz, without losing energy. But what exactly happens inside has remained a mystery.

A quiet tube with a heated grid inside. The voltage on the grid is suddenly raised, and the tube starts to hum, sustaining itself. This is not a malfunction but a transition to another stable state, like a ball rolling over a hill into a neighboring hollow.

A crystal of osmium dioxide, OsO₂, is like a stubborn teenager: under ordinary conditions it behaves like a typical metal, but press hard enough and its character changes.

A superconductor carries current without loss, like a perfectly smooth road where cars glide with no friction. But what if you scatter rocks and potholes across that road? Scientists decided to find out by adding disorder to a superconducting material just one atom thick.

Sound on a crystal surface is like ripples on water, but traveling through a solid. This ripple is called a surface acoustic wave: it moves a hundred thousand times slower than light, so it can be compressed into very short segments and fit on a tiny chip. Usually, such waves are launched by metallic combs made of aluminum or gold.

A crystal made of strontium, iodine, oxygen, and hydrogen looks like an ordinary white powder. But when you squeeze it with a force of hundreds of thousands of atmospheres, a rearrangement begins inside. Iodine atoms, which usually keep their distance, suddenly move closer and form new bonds.

A thin film of niobium and tin conducts electricity without resistance — until you make it really thin. Then it suddenly becomes an insulator. A team of physicists tested what happens when you add a bit more tin to the film than the formula calls for.

The layered material (SnS)1.15(TaS2) resembles a stack of paper, where the sheets conduct electricity and the interlayers prevent them from sticking together. At ambient pressure, this material conducts current without resistance, making it a superconductor.

A regular superconductor and a magnetic field are like water and fire: the field tears apart the electron pairs that carry current without resistance.

Sunlight hits a rooftop, and electrons are born in a thin film. They must reach the wires before they cool down and lose their energy. In tin sulfide, a cheap and accessible material for batteries, this sprint and cooldown has now been captured with unprecedented sharpness: frames follow every billionth of a billionth of a second.

Metal is like a rope made of many strands: pull too hard and it snaps. Engineers have long sought a way to make it both strong and flexible at the same time. Typically, additives that increase strength make the metal brittle. But a team of materials scientists found a loophole: they added a small amount of nitrogen to the CrMnFeCoNi alloy, just one atom in a hundred, and got an unexpected result.

In the crystal lattice of iron selenide, iron and selenium atoms alternate like bricks in a wall. But sometimes extra iron atoms sneak into the voids between them, like uninvited guests squeezing into the gaps between bricks.

The magnets in this crystal behave like guests at a party where everyone wants the same chair. No one can settle down for good, and from this chaos, a special state emerges. In it, spin momentum (what makes an electron a tiny magnet) manages to travel 480 micrometers.

A superconductor is a material where electric current flows without loss, like water through a perfectly smooth pipe. But if vortices appear, the current starts to 'stumble' over these tiny whirlpools. In graphene twisted at a special angle, such vortices can be created and studied one by one.

An ordinary superconductor works only in nature's freezer — at temperatures below minus one hundred degrees. The carbon-ball material K₃C₆₀ is no exception: without cold, it resists current like a crowd in a narrow corridor. But physicists noticed something strange: if you shine a laser on it, it starts conducting without loss even in warmth.

A cube of potassium tantalate behaves like an ordinary dielectric: it doesn't store an electric field. But grow this material as a thin film on a substrate of another crystal, and everything changes.