magnetophotonic effects

An orchestra without a conductor can sound harmonious if the musicians feel the common rhythm. In the world of solids, phonons play that role: quanta of crystal lattice vibrations. When atoms in a substrate start moving in circles, they can transfer their rotation to a magnetic layer on top and flip its magnetization.

A microwave oven heats food, but in the lab, microwaves have done something different: they turned a superconductor into a permanent magnet. A 300-nanometer-thick film of yttrium barium copper oxide, cooled to 80 kelvin, responded to 5-gigahertz radiation.

Two caravans travel toward each other along a narrow road. One is wide and slow, carrying a load of density. The other, a string of light carts carrying current, slips between the first. Thus, in a magnetron discharge, two structures rotating in opposite directions coexist: the density spoke and the current filaments.

The Sun breathes, and that breath has a magnetic rhythm. Every 27 days, the visible surface of the star makes a full rotation, and with it, its magnetic field, like an invisible ribbon wrapped around the star.

A magnetic field usually acts like a strict traffic cop: for heat to turn into electricity, it must stand across the road. If the field lies along the heat flow, the effect disappears, or so it was believed for decades. Scientists took an ultra-thin film of a magnetic oxide — a material where electron spins are aligned in a plane, like compass needles on a table.

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.

In the first moments after the Big Bang, the universe underwent a rapid expansion — inflation. Space stretched faster than light, and quantum jitters of the vacuum turned into real particles. This is how dark matter, the invisible substance that holds galaxies together, could have been born.

Ion current through a membrane is like a queue at a turnstile. Sometimes the turnstile is free — ions pass through quickly. Sometimes it gets stuck — the flow drops. A weak magnetic field, it turns out, doesn't push ions from behind; it simply changes the number of open turnstiles.

In 1956, two radio telescopes at Jodrell Bank stared at Sirius, capturing not an image but the trembling of intensity.

The flash lasts a thousandth of a second, but in that instant it releases as much energy as the Sun emits in a day. Such signals, fast radio bursts, have been caught by telescopes since 2007, and their source remains a mystery. A new study offers an elegant answer: it's all about a cosmic amplifier.

Inside planets and stars, in rotating oceans of plasma, turbulent flows, Coriolis forces, and magnetic tension collide. The central question is how the energy of this chaos crystallizes into a stable magnetic framework that can last billions of years.

A guitar string keeps vibrating even after the musician lets it go, and that vibration changes the sound the listener hears. Magnetic moments in a crystal behave much the same way: they align into a strict antiferromagnetic order (neighbors point in opposite directions), but they never completely freeze.

A beam of light enters frosted glass and fades — nothing unusual. But physicists have long known how to make light pass through without losing a single photon. This trick is called electromagnetically induced transparency: two light waves cancel each other at the right point, and absorption disappears. Now a similar feat has been pulled off with atoms.

The solar wind rushes from the Sun to Earth, but the magnetosphere bends the flow and sculpts it into plasma tails. The same motif plays out at the heart of galaxies: jets from accretion disks around black holes are twisted by the invisible hand of a magnetic field.

A surfer glides across the ocean surface until a big wave comes, and then they're flying forward. Similarly, a free electron interacts with light: usually the energy exchange is barely noticeable, but if the surrounding medium begins to oscillate rhythmically, each wave crest pushes the particle harder and harder.

A neat stack of atomic layers lies on a substrate. An invisible beam of terahertz light shines down on it, with a magnetic field applied from the side. After reflection, the beam's polarization rotates slightly.

A dead star with a magnetic field billions of times stronger than Earth's is a magnetar. Its crust cracks, sending a powerful X-ray burst into space. But some of that light doesn't reach us in its usual form. In an ultra-strong field, photons can turn into gravitational waves — the trembling of space itself.

Spacetime can be imagined as a tightly stretched fabric. A massive body dents it, guiding light. Rotation twists the fabric into a spiral. Such a gravitational funnel can entangle a passing photon with the very source of rotation — say, a tiny mirror. Quantum entanglement springs up: an invisible thread binding their fates.

A regular flashlight shines equally forward and backward. But in magnetic crystals, a axion appears — a ghostly excitation, like a wave going around a stadium: atoms pass a magnetic impulse to each other. When light meets an axion, a hybrid forms, whose fate depends on electric and magnetic fields.

Two magnets on a table either attract or repel — depending on how their poles are oriented. Inside each piece hide tiny regions where all the magnetic arrows point in the same direction. These regions are called domains, and their arrangement determines how the material behaves in an electrical circuit. In altermagnets, a new class of materials, domains are trickier.

In the orchestra of atoms, each instrument has its own score. But sometimes two musicians start playing in unison, and the sound amplifies many times over. In the quantum world, this 'harmony' is called a Feshbach resonance. It allows you to control atomic interactions with jeweler-like precision.

Quantum bits (qubits) are like delicate music in a noisy factory. Ambient magnetic fields constantly 'drown out' their quantum state, turning a coherent signal into cacophony. Usually, this destructive process is slowed by retuning the qubits themselves to different frequencies, but that doesn't always work.

A superconductor is like a perfect electron dance: electrons move in pairs without losing energy, like dancers who never miss a beat. But add a few magnetic impurities, and strangers crash into the dance, disrupting the synchronized motion. The temperature at which this dance begins drops.

A flashlight beam glides over uneven glass. The glass is massive galaxy clusters, and the flashlight is ancient light born shortly after the big bang. Passing by such clusters, light doesn't just bend around them like water around a rock. Its path shifts slightly sideways, and the amount of shift depends on how the light is 'twisted'—right or left.

Neutron stars are the ultra-dense remnants of stars, where matter is compressed to the limit described by Subrahmanyan Chandrasekhar. Magnetars are a type of neutron star with a magnetic field a quadrillion times stronger than Earth's.

In the quantum world, light and matter constantly exchange energy. Previously, they were described statically, like frozen poses. The new approach follows the dance itself: the transitions between states, like a continuous sequence of movements.

When two black holes merge, they shake the very fabric of spacetime. The newborn giant doesn't settle instantly (it rings like a cosmic bell, emitting a characteristic pattern of damped gravitational waves) the so-called ringdown.

The universe is not emptiness, but a vast crystalline sphere, threaded with invisible boundaries — domain walls frozen after phase transitions.

Light, like a shaken rope, oscillates in a specific plane. Astronomers and engineers often rotate images using a three-mirror system, the so-called K-mirror, but this inadvertently rotates the plane of oscillation as well. For precise measurements, that's a problem.

A vast, dark cloud of gas stretched across the young universe. Inside it, like invisible fingers, magnetic field lines left over from the very birth of the cosmos threaded through. These fields act on charged particles, pushing them together, like a gentle breeze gathering fallen leaves into piles.

A stack of magnetic plates, each magnetized opposite to its neighbor, is like a layered sandwich where electrons move as a single organism. The whole material starts mimicking an axion — a ghost particle that physicists suspect might be dark matter.

A superfluid gas behaves like a frictionless liquid. Two clouds of such gas are connected by a narrow bridge, and a stream of particles flows through it. This resembles the Josephson effect in superconductors, but here the particles are neutral atoms instead of electrons.

A piece of zinc oxide film lies on a table. A magnet is brought near, and slowly rotated around the film. The film, thinner than a human hair, begins to change its dimensions: now contracting, now stretching. This property is called magnetostriction — the ability of a material to deform under a magnetic field.

A swimmer cutting through water at the speed of the waves running on it finds themselves in a strange position: the waves they themselves generate can neither overtake them nor fall behind. They pile up at the swimmer's bow and freeze. A similar phenomenon occurs when a light source moves inside a medium at a speed matching the speed of energy transfer of the waves.

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.

Inside a barium titanate crystal, there's a built-in electric field, like a permanent magnet, but for charges. When a flash of light hits it, electrons are knocked loose and start darting around, colliding with atoms. But the crystal isn't the same in all directions: it has an axis along which the field is strongest.

You can make a light beam look like a flower with several petals. If you send such a beam through a cloud of cold rubidium atoms and switch on a magnetic field, the petals start to rotate. The angle of rotation is directly linked to the field's strength.

The Sun sometimes produces giant clouds of plasma that try to escape into space. But often they fail: an invisible magnetic cage keeps them near the surface. Such failed eruptions are called "trapped." Scientists built a computer model to understand exactly how this cage works.

A powerful laser strikes a tiny target, and it instantly turns into a cloud of scorching gas — plasma. Within this cloud, magnetic fields spontaneously arise. Like invisible hands, they prevent heat from freely escaping the hot core.

Magnetic moments in a crystal are like compass needles fixed at lattice sites. In the normal state, they line up in neat order, but if an electromagnetic wave strikes the crystal, the needles start to sway, like wheat stalks in the wind. These oscillations are called magnons, and they carry energy without the atoms themselves moving.