In recent times, a material called LK-99 has sparked intense global debates. A Korean research group shared their findings on arXiv, suggesting it might be a room-temperature superconductor, defying conventional limitations. If this holds true, it would be a monumental breakthrough, earning it the nickname “Holy Grail” of materials science. The potential impact on electricity generation, transportation, and motor usage is immense. However, doubts still linger.
At TU Wien, researchers conducted computer simulations on LK-99, revealing promising electron states that could support superconductivity. While not definitive proof, these discoveries underscore the significance of further exploration into this intriguing material.
The first step is the band structure
Immediately after the discovery of the new material LK-99, Prof. Liang Si from Northwestern University Xi'an and Prof. Karsten from TU Wien delved into computer simulations to analyze its properties. They focused on the crucial “band structure,” which reveals the possible combinations of velocity and energy for electrons in the material, providing insights into its electrical properties.
Using density functional theory, they calculated the band structure and found that LK-99 in its pure form would actually be a Mott insulator, lacking any current-conducting ability—a far cry from a superconductor. However, the experiments likely unintentionally used a doped version of the material, involving additional atoms. Doping altered the band structure, showing relatively flat lines, which can indicate potential mechanisms for superconductivity.
Another research group from Beijing confirmed this observation, stating that LK-99 is a paramagnetic insulator, requiring doping to enable the band structure conducive to superconductivity. Three other research groups conducted similar density functional theory calculations, obtaining comparable outcomes.
While not definitive proof, these findings fuel the hope that LK-99, with the right doping, could be the elusive high-temperature superconductor scientists have long sought after.
Superconductivity or diamagnetism?
Placing a superconductor on a magnet induces electric currents on its surface, generating a magnetic field that repels the magnet, causing the superconductor to float—an impressive sight demonstrated in a video with LK-99. Other experimental groups have since replicated these experiments, bolstering the claim that LK-99 might be a superconductor.
However, criticism arises as various forms of magnetism exist. Ferromagnetism, found in iron, allows attraction to a magnet and permanent magnetization. Paramagnetic materials can be attracted but not magnetized, while diamagnetic materials are repelled.
Prof. Held acknowledges that skeptics have considered LK-99 a diamagnet when floating above a magnet. Nevertheless, theoretical calculations suggest it's more likely to be paramagnetic, supported by Beijing experiments indicating LK-99 as a paramagnetic insulator. This suggests the levitation implies a transition to a superconducting state.
Though promising, Held remains cautious, acknowledging the need for further verification before declaring LK-99 the “Holy Grail” of materials science. The journey to confirm high-temperature superconductivity remains intriguing, and LK-99 indeed deserves closer scrutiny. The scientific community awaits with excitement.
Source: Vienna University of Technology