German Researchers: "LK-99 Is Not a Superconductor, But an Insulator"

Nature "LK-99 Single Crystal Created for Verification"
"Superconductivity-like Phenomenon Due to Impurities"

Researchers at the Max Planck Institute for Solid State Research in Stuttgart, Germany, announced that 'LK-99,' previously presumed to be a room-temperature and ambient-pressure superconductor, is not a superconductor.

"LK-99 Single Crystals Are Insulators, Not Superconductors... Superconductivity-like Phenomena Caused by Impurities Formed During Manufacturing"

[Image source=Yonhap News]

According to the international academic journal Nature on the 16th (local time), the Max Planck Institute research team led by Dr. Pascal Pufall succeeded in synthesizing pure single crystals of LK-99 but revealed that LK-99 single crystals are insulators, not superconductors.

In the study published on the 14th, the researchers stated that the superconductivity-like phenomena presented by the Korean research team were due to copper sulfide (C₂S) impurities formed during the manufacturing process of LK-99, concluding, "We exclude the existence of superconductivity."

Nature reported that "there are limitations since the international research team did not receive LK-99 samples from the Quantum Energy Research Institute for verification," but also noted that the German researchers' conclusion disappoints those hoping that LK-99, composed of copper, lead, phosphorus, and oxygen, would be the first-ever room-temperature and ambient-pressure superconductor.

Unlike the Korean and other foreign research teams who heated LK-99 in a crucible during verification, the German team succeeded in producing pure LK-99 single crystals without copper sulfide impurities by using the "floating zone crystal growth" technique, which prevents sulfur (S) penetration.

The LK-99 single crystals produced by the German team exhibit a transparent purple color. Experimental results showed that these single crystals are insulators with resistance reaching millions of ohms (Ω), not superconductors, and they exhibit slight ferromagnetism and diamagnetism but are not strong enough to levitate above a magnet.

Dr. Pufall explained, "The traces of superconductivity found in LK-99 originated from copper sulfide impurities absent in the single crystals. Having single crystals allows us to clearly understand the intrinsic properties of the system."

"Caution Against Premature Calculations, Lessons from LK-99"

The appearance of the LK-99 single crystal, claimed to be created by German researchers. It has a transparent purple hue.
[Photo by Pascal Puphal, Dr. at Max Planck Institute for Solid State Research · Nature]

Leslie Soob, a solid-state chemist at Princeton University, said, "Even before LK-99, I gave lectures warning about density functional theory (DFT) related to superconductivity phenomena," adding, "The LK-99 case clearly reveals the lessons from premature calculations."

Nature reported that while some critics point to the LK-99 case as a model of scientific reproducibility, others noted that this highly publicized so-called 'grand challenge' was resolved unusually quickly.

Professor Davis Visik of UC explained, "When copper oxide superconductors were discovered in 1986, many researchers rushed to investigate their properties, but debates continue even after nearly 40 years. In comparison, efforts to clarify LK-99 were accomplished easily, which is relatively rare."

Meanwhile, the Quantum Energy Research Institute declined to comment to Nature, but regardless of Nature's conclusions, verification efforts by domestic research teams are ongoing. The verification committee, composed of experts from the Korean physics community, recently secured the materials necessary for synthesizing LK-99 and has begun full-scale sample production. A conclusion is expected by the end of this month.

This content was produced with the assistance of AI translation services.