Les bandes plates dans les métaux kagome pourraient débloquer les futurs supraconducteurs

Nouveaux progrès dans les supraconducteurs kagome

Superconductors are materials that carry electricity without resistance, but until now, they have only worked under extreme conditions. Kagome metals may change that.”
This grounds readers who may not be physics-savvy.

En novembre 2024, nous avons discuté d’un nouveau matériau pour de nouvelles théories magnétiques, développé par des chercheurs de l’Université Rice.

This discovery was built upon une publication de 2022, in which researchers discovered that “le matériau kagome,” a type of metallic crystal, exhibits surprising magnetic properties.

It takes its name from the kagome weaving pattern used in traditional Japanese craft, or trihexagonal tiling, with overlapping triangles and large hexagonal voids.

Source: Research Gate

In a similar way, kagome materials, like, for example, magnetic iron-germanium crystals, are organized in this pattern at the atomic level.

Another chromium-based kagome metal, CsCr₃Sb₅ (cesium-chromium-antimony), seems to have massive potential for future electronics components, including superconductors, topological insulators, and spin-based electronics, according to the latest paper by Rice University researchers, published in Nature Communications¹, under the title “Spin excitations and flat electronic bands in a Cr-based kagome superconductor”.

Propriétés magnétiques et électroniques des matériaux kagome

Already in 2022, unique properties of the kagome material had been noticed:

• Magnetic effects require electrons to flow around the kagome triangles, akin to superconductivity.
  • Although these magnetic and charge density wave effects are not superconductivity in the conventional sense, researchers have confirmed that such phenomena in kagome materials can persist even at room temperature and normal pressure conditions. This makes them valuable stepping stones toward discovering higher-temperature superconductors.
• The presence of a “charge density wave“, where the electrons “merge” into each other into a collective wave, collectively carrying an electric current.
  • Unlike “normal” superconductivity, this comes in spikes, like water dripping from a faucet, more than a continuous electron flow.
• Despite displaying charge density waves, kagome materials also display magnetic properties, which are usually 2 incompatible properties.

Overall, the very organized nature of kagome materials could make them easier to study phenomena at the very edge of our understanding of electromagnetism, like “unconventional superconductivity” or “the continual fluctuations between magnetic states in quantum spin liquids”.

Fabrication d’un supraconducteur kagome

Bande plate Électrons 

Électrons à bande plate are electrons in a special type of electron energy band that has a constant energy, or “flat” dispersion, meaning electrons have the same kinetic energy regardless of their momentum.

Less technically, this means a super-dense state, where electrons can behave like superconductors, but without the usual pre-requisite conditions for superconductivity (ultra-cold, or ultra-high pressure).

So far, stabilizing kagome lattices to bring flat bands to the energy level required has been difficult to achieve. Until CsCr₃Sb₅ was used.

“Our results confirm a surprising theoretical prediction and establish a pathway for engineering exotic superconductivity through chemical and structural control,”

Pengcheng Dai – Rice’s Department of Physics and Astronomy

Construire le bon cristal

CsCr₃Sb₅ naturally crystallizes in a layered hexagonal lattice.

Source: Nature Communications

However, to observe the effect at scale and have a material that will be useful for later commercial applications, a much larger crystal was required.

Refining on their previous methods, the researchers managed to produce samples 100x larger than previously done.

Analyse ARPES et RIXS du supraconducteur kagome CsCr₃Sb₅

To visualize the electronic structure of CsCr3Sb5, the researchers used a technique called ARPES (angle-resolved photoemission spectroscopy ). It creates a map of the electron under light generated by a particle accelerator (synchrotron).

Source: Nature Communications

It revealed distinct signatures associated with compact molecular orbitals, a sign of electronic flat bands, and confirmed that all of the polarization geometries contribute to the formation of flat bands.

“The ARPES and RIXS results of our collaborative team give a consistent picture that flat bands here are not passive spectators but active participants in shaping the magnetic and electronic landscape.

Qimiao Si – Rice’s Department of Physics and Astronomy

They then used RIXS (resonant inelastic X-ray scattering) to measure the magnetic excitation states.

This too confirmed the presence of flat bands, independent of the ARPES’ results.

Source: Nature Communications

Effets de la température sur le potentiel de supraconductivité kagome

The scientists then checked the effect of temperature variation on the properties of this new material.

Contrary to other potential superconducting materials, the properties were better at 140°K (-133°C / -207°F) than at 10°K (-263°C / -441°F).

Source: Nature Communications

Overall, these experiments not only identified a very promising new material but also demonstrated that the lattice geometry is directly connected to emergent quantum states.

“By identifying active flat bands, we’ve demonstrated a direct connection between lattice geometry and emergent quantum states,”

Ming Yi – Rice’s Associate Professor of Physics and Astronomy.

Applications potentielles

The density of states from the flat bands is at the energy levels near a quantum critical point, potentially enabling superconductivity.

This is also an improvement over the previous kagome metal lattice, as kagome flat bands provide a high density of states across a much larger portion of the material.

CsCr3Sb5 also suppresses the density wave observed in other kagome materials, improving its superconductivity potential further.

A high- or room-temperature kagome superconductor would be revolutionary for quantum computing, spintronics electronics components (low energy consumption electronics), and topological materials (similaire au nouvel état de la matière développé par Microsoft (MSFT ) équipe de calcul quantique).

It could also have potential as “just” a high-temperature superconductor, which would be usable in maglev, military technology, and power generation.

Glissez pour faire défiler →

Leaders in Superconductivity Solutions

American Superconductor Corporation

AMSC est une entreprise qui fournit des solutions énergétiques pour le réseau électrique, les navires et l’énergie éolienne. En général, plus un système consomme d’énergie ou est massif, plus il nécessite une technologie supraconductrice pour éviter la surchauffe.

Malgré son nom, ASMC fournit non seulement des systèmes supraconducteurs mais aussi, par exemple, des transmissions d’engrenages pour les éoliennes.

L’entreprise bénéficie de plusieurs moteurs de croissance, de la tendance à l’électrification et à la numérisation (y compris les centres de données IA), mais aussi du rapatriement des capacités de fabrication américaines et du besoin pour les marines du monde anglophone de se moderniser face aux risques géopolitiques croissants.

Source: American Superconductor Corporation

Dans le segment de l’alimentation électrique, AMSC a constaté une hausse constante des commandes. Cela a été stimulé par les usines de semi-conducteurs cherchant à être protégées des fluctuations du réseau, à aider le réseau à gérer la nature intermittente des énergies renouvelables, ainsi que par l’alimentation et les contrôles sur les sites industriels.

Dans le segment des éoliennes, AMSC est principalement actif avec son Système de Contrôle Électrique (ECS). Historiquement, l’ESC était un segment fort pour l’entreprise avec les éoliennes de 2 MW, mais il a progressivement décliné. AMSC vise un rebond grâce au nouveau design d’éolienne de 3 MW, avec un accent particulier sur le marché indien.

Source: American Superconductor Corporation

Pour les navires militaires, ASMC fournit le « Contre-mine magnétique supraconducteur à haute température d’AMSC », un système qui modifie la signature magnétique des navires pour les protéger des mines marines. Il est vendu aux marines américaine, canadienne et britannique, avec 75 M$ de commandes à ce jour.

Dans l’ensemble, ASMC excelle en exploitant la technologie supraconductrice dans des applications de niche viables aujourd’hui, tout en étant probablement prête à déployer d’autres avancées à l’avenir. Les investisseurs doivent également noter que l’action a connu une volatilité extrême par le passé, et ils doivent évaluer les risques en conséquence.

Dernières nouvelles et développements de l’action American Superconductor Corporation (AMSC)

Étude référencée

^{1. Wang, Z., Guo, Y., Huang, HY. et al. Spin excitations and flat electronic bands in a Cr-based kagome superconductor. Nature Communications 16, 7573 (2025). https://doi.org/10.1038/s41467-025-62298-5}