A new quantum state of matter behaves as if it doesn’t fully belong to a world with two or three dimensions of space, revealing a previously unobserved way for electrons to move.

Physicists categorise states of matter based on how electrons move within a material. This motion depends on many factors, such as the arrangement of the material’s atoms.

When a thin material is immersed in a magnetic field, its electrons trace tiny circles, and any stream of them is pushed to the material’s side. This is known as the Hall effect. For materials that are magnetic, electron choreographies become more complex, giving rise to different versions of this effect.

at Nanjing University in China and his colleagues unexpectedly discovered a new version of this phenomenon, which they call the transdimensional anomalous Hall effect (TDAHE).

The team was studying electrons in a made from carbon atoms arranged in a pattern of hexagons in hopes of seeing them form perfectly efficient currents. But when they immersed the material in a magnetic field, the electrons reacted oddly.

“TDAHE came about as a complete surprise, a phenomenon never seen in any other material before, nor does any theory predict that,” says Wang. “After we measured the raw data, we spent about one year [trying] to understand it.”

Subscriber-only newsletter

Sign up to Lost in Space-Time

Sign up to newsletter

Specifically, what stumped the researchers was that their material exhibited a type of Hall effect when they applied two different, mutually perpendicular magnetic fields. This means the electrons could execute looping motions both horizontally and vertically, even though the material was supposed to be too thin to accommodate both.

Wang says he and his colleagues initially thought some experimental error was to blame, but several follow-up experiments kept confirming that their measurements were correct. Making and testing more samples of the materials showed the same. They had to conclude that for pieces of their carbon material between 2 and 5 nanometres thick, the electrons were simply doing something new.

Because these thicknesses don’t make the material fully two- or three-dimensional, the team named the new electronic state accordingly. It doesn’t somehow bridge two- and three-dimensional realms, says Wang. “It is also not a little bit of 2D and another little bit of 3D. By using ‘transdimensional’, we want to express that there exists a new regime, which does not belong to previously well-studied 2D or 3D cases,” he says.

Solving the 250-year-old puzzle of how static electricity works

You may think you know static electricity, but its true nature has long eluded scientists. We’ve now made a huge leap towards finally figuring it out

at the University of California, Santa Barbara, says that what sets the new state apart is that the mathematical representation of the electrons’ states lacks symmetry in three different ways, which is novel compared with similar states. In his view, this is more of a defining feature than the dimensionality of the material – its thickness is just a means to an end, he says.

Young says the new state can be thought of as a type of “quarter-metal”, or a metal where the lack of symmetry limits what the electrons can do compared with more conventional metals.

Wang’s team now wants to look for what they term transdimensional physics in other materials and to use more instruments, such as diamond-based magnetic field sensors, to learn more about the new state.

These days, our lives revolve around the digital world. Money, culture, news, gossip – all of it lives there. Generative artificial intelligence is the biggest story in the world, but could you point to where that technology is physically located? The material world just isn’t where the action is.

And yet, despite appearances, we still live in a material world. We need steel for building, lithium and cobalt for batteries, and (despite our best efforts) oil to power our vehicles. Materials might not be sexy, but they still undergird our way of life and shape world events.

We may now be on the cusp of something radical: a completely new way to understand materials. History teaches us that the consequences could be huge. The last time we had such a groundbreaking idea in materials science, it was the late 1920s, with discoveries about the way electrons occupy particular energy levels – or bands – and the gaps between them. This presaged the development of the transistor, the basic unit of all computer hardware, including the chips that power modern AI.

But researchers have long suspected that the innards of materials contain more than those simple energy bands. They may also have a subtle, undulating quantum topography that could determine their properties. And as we report in our cover feature (see “We’ve glimpsed the secret quantum landscape inside all matter”), we are now charting this quantum landscape for the first time.

Materials may have a subtle, undulating quantum topography

This deeper exploration could lead to discoveries as revolutionary as the transistor. One hope, for example, is a material that conducts electricity with zero resistance at room temperature.

Finding one of these superconductors would mean we could transmit electricity with no loss in power, a serious boon to green energy and our fight against climate change, among other things.

Even better, this probing could lead us to some new kind of material that we haven’t foreseen at all. Far from retreating from the material world, we might be on the brink of expanding its horizons.

Cement that can cool itself by reflecting light on the outside and releasing heat from its surface could help buildings stay comfortable without needing air conditioning.

Normal cement tends to absorb infrared radiation from the sun and store it as heat, which can increase the temperature inside cement buildings as well as that of the surrounding air.

So then at Southeast University in Nanjing, China, and her colleagues decided to address this by creating a cement in which tiny reflective crystals of a mineral called ettringite collect on the surface.

The team’s cement emits infrared light from its surface, rather than storing it, and so loses heat quickly. “It works like a mirror and a radiator, so it can reflect sunlight away and send heat out into the sky, so a building can stay cooler without any air conditioning or electricity,” says Du.

To make it, the researchers first produce tiny pellets from common minerals like limestone and gypsum. These are ground to dust and mixed with water before being poured into a silicone mould covered in small holes. Air bubbles passing through the holes create slight depressions in the cement’s surface, where the reflective ettringite crystals can then grow, while an aluminium-rich gel in the set cement lets infrared light pass through the material.

This process is easily scalable, says Du, and the cement is $5 per tonne cheaper than regular Portland cement because it can be produced at lower temperatures.

Free newsletter

Sign up to The Earth Edition

Sign up to newsletter

Du and her team tested how their cement kept cool on a hot roof at at Purdue University in Indiana, which jointly hosted Du’s PhD project, finding that the surface temperature was 5.4°C (9.7°F) lower than the air and 26°C (47°F) lower than the Portland cement.

“It’s a useful material,” says at University College London. “You increase the reflective capacity as well as increasing the emissivity, so any energy that is captured or conducted to the material is emitted efficiently back.”

However, measuring only the surface temperature of the material doesn’t tell us how it will perform in the real world, says Brousse, so it should undergo further testing. “It doesn’t mean that because the surface is 5°C lower, that the air temperature will be 5°C lower around it. The effect locally may be greatly limited.”