Pre printed paper has been published, please draw a conclusion? Chinese Academy of Sciences discovers the root cause of the illusion of "room temperature superconducting materials" LK | Center for Quantum Materials Science at Peking University | False Image

"Our work points out the reason why LK-99 is mistaken for superconductor," Luo Jianlin, a researcher and doctoral supervisor of the Institute of Physics of the Chinese Academy of Sciences, told Pengpai Technology.

A preprint paper from the research team of the Chinese Academy of Sciences recently published on the arXiv website may end "LK-99 is a room temperature superconductor".

Recently, due to the claim by a South Korean research team that LK-99 material can conduct superconductivity at room temperature, preprint research papers on LK-99 have flooded the arXiv website. But it may be coming to an end soon: the latest preprint paper published on the arXiv website not only suggests that LK-99's room temperature superconductivity is a false phenomenon, but also identifies the reason for this false phenomenon - copper sulfide impurities.

In addition, research teams from institutions such as the Center for Quantum Materials Science at Peking University and Princeton University in the United States have also submitted preprint papers, stating that although they have observed that their "fired" LK-99 samples do not exhibit superconductivity and are more like magnets rather than room temperature superconductors.

On August 9, Luo Jianlin, one of the correspondence authors of the above-mentioned paper and a researcher and doctoral supervisor of the Institute of Physics of the Chinese Academy of Sciences, told Pengpai Technology, "Our work pointed out the reason why we mistook LK-99 for superconductor." "The experimental results show that it is a false image, which is derived from cuprous sulfide." "LK-99 is not superconducting! Although the relevant samples have weak diamagnetism, they do not have complete diamagnetism, and there is no zero resistance phenomenon."

The paper was submitted to the arXiv website at 15:59 on August 8th and has now been publicly released.

Team of Institute of Physics, Chinese Academy of Sciences: LK-99 looks like superconductivity, but actually it is not. Cuprous sulfide leads to illusion

Copper sulfide is one of the raw materials for firing LK-99. LK-99 is a copper doped lead apatite material with a composition of Pb10-xCux6O (0.9). Current experimental evidence suggests that superconductivity cannot be achieved by increasing or decreasing the content of cuprous sulfide in the sample or other methods.

The aforementioned paper states, "We believe that the so-called superconducting behavior in LK-99 is likely due to the first-order structural phase transition of cuprous sulfide around 385K, which occurs at high temperatures." β Phase transition to low-temperature γ This leads to a decrease in electrical resistivity

According to a previous report by The Paper, on the morning of July 22nd, a research team from the Korean Quantum Energy Research Center submitted two similar papers on the preprint website arXiv, claiming that a copper doped lead apatite material named LK-99 has "room temperature+atmospheric pressure" superconductivity. Subsequently, multiple international research teams began to repeat experiments, attempting to synthesize LK-99 to replicate the experimental results of the Korean team. The relevant news has also had an impact on global stock markets.

At 16:13 on July 31st, Professor Liu Zhiqi's team from the School of Materials Science and Engineering at Beihang University submitted their paper on the preprint website arXiv. The paper states that the room temperature resistance of the synthesized LK-99 sample is not zero, and no magnetic levitation phenomenon was observed; This material is similar to a semiconductor, not a superconductor.

At 14:59 on August 2nd, Sun Yue, a professor and doctoral supervisor at the School of Physics at Southeast University, submitted a paper on the preprint website arXiv, stating that the LK-99 sample measured zero resistance at temperatures above 100K, but did not exhibit diamagnetism. Sun Yue stated in the video that a total of 6 samples were tested, but zero resistance was observed in only 1 sample, and most of the other samples exhibited semiconductor behavior. The paper states, "Our findings suggest that Pb10-xCux6O may become a candidate material for searching for high-temperature superconductors."

Team from Peking University Center for Quantum Materials Science: Observed LK-99 sample as "semi suspended" but without superconductivity

At 13:34 on August 6th, researchers from the Center for Quantum Materials Science at Peking University submitted a research article titled "Ferromagnetic Semi Suspension Phenomenon of LK-99 like Synthetic Samples" on the preprint website arXiv.

The paper states that magnetic semi suspension under environmental conditions is considered a "spectacular and easily obtainable" phenomenon, and has therefore been a focus of experimental verification of LK-99 materials. Although the research team at Peking University successfully observed the phenomenon of "magnetic semi suspension" in some sheet-like small fragment samples, it was measured that there was no Meisner effect or zero resistance in the samples, so they did not have superconductivity. The experimental results indicate that the samples generally contain weak but definite soft ferromagnetic components.

The research team believes that soft ferromagnetism is sufficient to explain the semi suspension phenomenon of its samples in a strong vertical magnetic field. The paper states, "Recent calculations have shown the presence of flat band electronic structures in Pb10-xCux6O, which may lead to spontaneous ferromagnetism and warrant further investigation."

Associate Professor Jia Shuang, Researcher and Doctoral Supervisor at Peking University Center for Quantum Materials Science, and Associate Professor Li Yuan are the corresponding authors of the aforementioned paper.

Huazhong University of Science and Technology team: The sample can be "semi suspended" at a large angle, but the resistance has not been measured

At 3:13 am on August 3rd, Professor Chang Haixin's team from the School of Materials Science and Engineering at Huazhong University of Science and Technology, who had caused a sensation by publishing a video of the LK-99 validation experiment on the Bilibili website, submitted a paper on the preprint website arXiv and publicly disclosed their experimental progress. The title of this paper is "Successful synthesis of LK-99 and room temperature atmospheric pressure magnetic levitation".

The paper states that they have successfully synthesized LK-99 material, which can be "semi suspended" at a large angle at room temperature and environmental pressure. "Our research findings demonstrate the importance of crystallinity and appropriate copper doping, highlighting the underlying superconducting mechanism of copper oxygen induced band changes in this phosphate oxide. We look forward to more consistent testing, such as electrical testing at room temperature, which will demonstrate the enormous potential of this phosphate oxide."

On August 1st, Huazhong University of Science and Technology released a video on the domestic website Bilibili about the repeated experiment of LK-99 materials, which became popular on social media both domestically and internationally. The relevant videos are listed as supplementary materials to the aforementioned paper.

The introduction of the relevant video states, "Under the guidance of Professor Chang Haixin, postdoctoral researcher Wu Hao and doctoral student Yang Li from the School of Materials Science and Technology of Huazhong University of Science and Technology have successfully synthesized the LK-99 crystal that can be magnetically suspended for the first time. The suspension angle of the crystal is larger than that of the sample obtained by Sukbae Lee et al., and it is expected to achieve true non-contact superconducting magnetic suspension."

The publisher of the relevant video stated that the resistance of the relevant samples has not been measured yet. Because measuring resistance requires micro/nano processing, the sample is damaged. At present, there is only one very small sample, so I dare not move it. I really dare not move it. We are urgently "firing" the third batch of samples.

Joint team from Princeton University and other institutions in the United States: LK-99 sample transparent, excluding superconductivity

On August 9th, a preprint paper from Princeton University in the United States caught people's attention before it went viral. This paper confirms the experimental results and conclusions of the research team at the Quantum Materials Science Center of Peking University.

Although the aforementioned paper from Princeton University in the United States has been submitted, it has not yet been officially published on the preprint website. The author has uploaded it to the website and shared it on social media on the 9th.

The research related to this paper was jointly completed by researchers from the Department of Physics and Chemistry at Princeton University in the United States, the Department of Chemistry and Biochemistry at the University of Oregon in the United States, and the Max Planck Institute for Solid State Chemical Physics in Germany.

The paper states that in a recent series of reports, doped apatite lead is considered a candidate for room temperature and atmospheric pressure superconductors. However, from both experimental and theoretical perspectives, these claims have largely not been confirmed. For this purpose, the research team synthesized LK-99 samples, but the analysis results showed that their samples did not exhibit high-temperature superconductivity.

A preprint paper jointly completed by researchers from the Department of Physics and Chemistry at Princeton University, the Department of Chemistry and Biochemistry at the University of Oregon, and the Max Planck Institute for Solid State Chemical Physics in Germany suggests that the LK-99 sample is more likely to be a magnet rather than a superconductor at room temperature and pressure.

Researchers have calculated that the hexagonal channels of the material may contain OH - anions instead of divalent oxygen anions; Moreover, the substitution of copper is thermodynamically very disadvantageous. "The phonon spectra of the balanced structure exhibit many unstable phonon modes." "Although attempts were initially made to model LK-99 in this way, it is still questionable whether copper enters the structure at a meaningful concentration." "This band is unlikely to support strong superfluidity and is prone to ferromagnetism at low temperatures." "In short, Pb9Cu62 is more likely to be a magnet rather than a room temperature and atmospheric pressure superconductor."