Southeast University successfully tested LK-99 zero resistance in the world! Is human history approaching the transition point？
Zhiyuan Xin reports.
Editor: editorial department
[Introduction to Zhiyuan Xin] Room temperature superconductivity is not far from human beings? At 1 am, Southeast University successfully observed the zero resistance phenomenon of LK-99 material at the temperature of 110K for the first time, which attracted many netizens to watch.
Just a little after midnight today, Sun Yue, a physics professor at Southeast University, sent out a video of bilibili, which once again set off a frenzy of discussion among netizens all over the world.
In the video, Professor Sun Yue said that the team successfully observed the zero resistance of LK-99 under normal pressure at a temperature below 110 K (-163 C).
This is an important evidence that LK-99 may have superconductivity.
However, Professor Sun Yue also stressed that the current results can not confirm that LK-99 is room temperature superconductivity, and further exploration and measurement are needed.
Although it's only a small step, it doesn't delay bilibili netizens from rushing into the barrage area to take a photo and punch in.
At the same time, this research has once again topped the hot list of well-known foreign forums.
"Xizhixi", a professor of physics at South China University of Technology, commented on this: "The result of Southeast University is very shocking, even more shocking than that of China University of Science and Technology the day before yesterday. 」
Combining these four studies, it seems that the confidence of Korean team research has become much higher.
However, if zero resistance can be observed at 110K under the condition of a large number of impurities and normal pressure, then as long as the purity/pressure is increased, it may be expected to get a real "room temperature superconducting" material!
Now, it seems that the research of the Korean team is likely to make human history reach the transition point ahead of time. If we get the right tree of science and technology this time, our imagination can already rush out of the earth and rush to the universe.
In order to obtain superconductivity at normal temperature and pressure, human beings have been working hard for more than 100 years.
LK-99 zero resistance phenomenon was observed below 110K for the first time.
This work was completed by Hou Qiang, Wei Wei and Zhou Xin, as well as Professor Sun Yue and Professor Shi Zhixiang, and has been uploaded to arXiv.
Address: https://arxiv.org/pdf/2308.01192.pdf.
In the experiment, the team measured six samples, but only one sample measured zero resistance. Most of the other samples show the behavior of semiconductors.
For samples with zero resistance, the team also measured the Messner effect (that is, complete diamagnetism), but this effect was not observed.
Based on this, the team speculated that if the zero resistance phenomenon in the sample is caused by superconductivity, then its superconducting composition is still relatively low.
"Zero resistance" appeared?
It can be seen that the resistance of the sample is measured at low temperature from 300K, and the current is 1mA.
The team said that because the sample itself is a little brittle, it is difficult to make it into a regular shape. Therefore, in order to save time, the sample was adjusted to an irregular shape and the resistivity was measured by the four-wire method.
It can be seen that at high temperature, the sample shows some semiconductor characteristics.
However, when the temperature gradually decreases to 110K, the resistance of the sample basically drops to 0.
Specifically, the resistance at this time is about 10-5 to 10-6 ohms, and the voltage at this time is about 10-8 or 10-9 volts at a current of 1mA, which is already the limit of the measuring instrument PBMS used, so it can be considered that zero resistance is observed.
At about 250K, there was a strange phenomenon of resistance drop, and the reason is still unknown. Professor Sun Yue speculated that the motor might not be clean enough.
The picture on the right shows the superconducting transition of the sample after adding a magnetic field.
It can be seen that the superconducting transition of the sample is relatively stable under the magnetic field, and the transition temperature changes only a little.
However, it can also be seen that the superconducting transition of the sample under magnetic field is also somewhat strange.
For example, at low field, with the increase of magnetic field, the superconducting transition region of the sample will tend to the low temperature region.
However, at 9 Tesla and 7 Tesla, this area returned to the high temperature area a little, and the reason cannot be explained.
The purity of LK-99 sample is higher than that of Korean team.
The figure below shows the results of X-ray diffraction. On the left, two precursors are measured, and on the right, four samples made by the team are measured.
After comparison, it can be found that the X-ray results of the samples are very consistent with those of the Korean team.
Look carefully at the picture below, the peak is very small, so the purity of the team's samples is higher than that of the Korean team.
South China University of Technology: The result is shocking.
"Xizhixi" of South China University of Technology said that the result of Southeast University was even more shocking than that of Huake the day before yesterday, because modern magnetic measuring instruments have high sensitivity and can detect very small magnetic signals.
However, it is much more difficult to measure the resistance signal because it requires many conditions, such as continuous and uniform samples, well-made electrodes, and no oxidation on the surface.
Therefore, the process of measuring zero resistance is very time-consuming and laborious, and it is unexpected that the team of Southeast University can measure it so quickly.
"Xizhixi" said that the quality of the experimental data of Southeast University was very high, which clearly showed the whole process of resistance dropping to zero.
It can be said that the transition temperature of 110K has far exceeded expectations. The first copper oxide material to win the Nobel Prize has a transition temperature of just over 20 K..
As for six samples, only one has measured zero resistance, which should be because the samples are uneven and the doping ratio changes greatly.
Source: Xizhixi
There is no need to worry about the measurement accuracy of PPMS, and zero resistance is measured, that is, zero resistance.
Moreover, if the temperature of resistance decreases by three or four orders of magnitude, superconductivity may exist, and the result of Southeast University is even better.
Perhaps from today, our imagination of room temperature superconductivity can be a little wilder.
This exciting result also indirectly shows that the possibility of Korean team data fraud is almost zero.
The well-known UP owner "Turing's Cat" also analyzed that this experiment basically confirmed that the first paper was not nonsense. It has certain support for IBS theory and BRBCS theory, even dating back to the Soviet Union in the last century.
In addition, the friend "ALLBLUEandgrey" said: 110K should be a good level in the existing atmospheric superconductivity, although it does not exceed the existing maximum temperature (135K/138K).
Even, some netizens have imagined that human beings will never have to roll again!
American Research Center: The data is wrong.
However, for the experiment of Southeast University, the Center for Condensed Matter Theory (CMTC) of the University of Maryland in the United States pointed out that there is the possibility of wrong drawing of numbers.
CMTC issued a document saying that
From the linear scale, there seems to be no transition, which is very disappointing and not a good sign, because synthetic materials are also faintly visible.
CMTC said that the "physics" displayed in these unconfirmed preprints is simply a great record in the world. There is no obvious SC transition in the original paper, T.
This data error was first discovered by the Solid State Quantum Physics Laboratory of Kyoto University.
"When the vertical axis is set to a linear scale (originally logarithmic), there appears a sharp change that seems to be superconducting transition. 」
Similarly, some friends also pointed out that the jump of resistance curve in the study is not obvious enough. Although the resistance at 110k is very small, it cannot be guaranteed to be zero resistance.
In the message area of bilibili video, some netizens also questioned the reliability of resistance data.
Northwest University Research: LK-99 Anti-magnetic levitation is superconductivity?
On August 2nd, a paper by a researcher from Northwest University seemed to advance the conclusion that LK-99 is likely to have superconductivity.
A paper published by researchers from Northwestern University in China and Austrian Institute of Solid State Physics suggested that the structure of LK-99 indicated that it should have strong paramagnetism.
If it can show the phenomenon of magnetic levitation, the reason may only come from superconductivity, rather than a separate "diamagnetism."
After various teams around the world successfully reappeared the magnetic levitation state of LK-99, the rigorous audience emphasized that the floating phenomenon can only show that LK-99 has "diamagnetism", and it needs further confirmation that LK-99 in the experimental material can show superconductivity at room temperature.
Address: https://arxiv.org/pdf/2308.00676.pdf.
This paper provides a theoretical basis that the magnetic levitation phenomenon reappeared in all countries in the world can't come from "individual diamagnetism", but according to the existing theory, it can only come from superconductivity.
This paper thinks that the diamagnetism of LK-99 comes from superconductivity, because if it only has diamagnetism, it will contradict the experiment and calculation in the paper.
If the diamagnetism in the experiment of Huazhong University of Science and Technology is true, this paper provides evidence to prove the superconductivity of the material. If you doubt the validity of the paper, please note that one of the authors has an H-index of 67.
Basic logic in the paper
Just like the paper published by the National Natural Laboratory the day before, researchers used a calculation method called Density Functional Theory (DFT) to study the properties of copper-substituted apatite.
They found that LK-99 has some special "band structure" near Fermi level (a key energy level).
This similar result often represents a high transition temperature in many known superconducting substances.
And as shown in Figure D above, these two "narrow energy bands" have three electrons in each cell. Therefore, Cu is basically in a state of effective electronic configuration. However, this "narrow band" structure and new electronic configuration both mean strong paramagnetism.
Therefore, if, as many people suspect, the reappeared LK-99 shows that the source of magnetic levitation state is only "diamagnetism" and there is no superconductivity, it will contradict the conclusion in the paper.
Therefore, the author thinks in the paper that if LK-99 can show the magnetic levitation state, theoretically, it may only come from its superconductivity.
AI Daxie eats melons online
The heat of room temperature superconductivity also alarmed AI bosses.
For example, Sam Altman, CEO of OpenAI, quipped that now headhunters are starting to recruit people with "two years of LK-99 related experience".
But think about it, the Korean team has been working with the mentor for 20 years, and 2 years of experience seems to be not too much. (dog head)
Andrej Karpathy, a research scientist at OpenAI, also said that a month ago, the hottest horse was the duel between Musk and Xiaozha. Now the hot spot in the whole network should be room temperature superconductivity, which will appear soon.
And interestingly, Karpathy seems to have officially announced to join the "I want to believe" religion in the tweet and started the online prayer mode. I hope it can come true!
Jim Fan, a senior research scientist at Nvidia, lamented that all of a sudden, all the AI experts on the Internet have turned into experts in materials science, and the speed of human "learning" new knowledge is really faster than GPT-4.
At the same time, he also summarized the similarities between artificial intelligence and LK-99:
-Both are "modern alchemy"
-The Holy Grail is simpler than we thought
-There are many hyperparameters to adjust.
-Random seeds are important
-arXiv is a new battlefield
-Expansion is the key.
-Every update will break the circle
-Twitter experts are the fastest growing.
-There will be "GPT-4" from big companies and "Alpaca" from grassroots.
Science once again issued a document: room temperature superconductivity? New progress
On August 1st, Dr. Derek Lowe of Duke University, who had published a key comment on Science, updated a follow-up article.
Of course, the first thing mentioned was the bilibili video of Sekinoyamaguchi Male Technician, the master of the UP of China University of Science and Technology, detonating the whole Chinese Internet.
He pointed out that the LK-99 sample in the video can be suspended on the magnet, and the direction is different from the magnet itself.
This phenomenon is very important. If it is only a magnetic material, the product will return to a specific place like a compass. Superconductors, on the other hand, are perfect diamagnets, which can eliminate the influence of all magnetic fields. This is a big difference.
However, Lowe also said that there may be other explanations for the magnetic levitation of the samples in the video that have nothing to do with room temperature superconductivity.
At the same time, these two papers from Shenyang National Research Center of Materials Science, Institute of Metals, Chinese Academy of Sciences, and Sinéad Griffin, a researcher from Lawrence Berkeley National Laboratory, are also crucial.
From the method point of view, they all started from the X-ray structural data of LK-99 and predicted the superconductivity of LK-99 through density functional theory (DFT) calculation.
Moreover, the same conclusion is reached: theoretically, LK-99 has the possibility of room temperature superconductivity.
This conclusion is of great significance-that is, we don't need to assume a new physical system to explain LK-99.
Of course, it is not so easy to reproduce room temperature superconducting products, but it also means that many people will try.
In this process, many unknown variables may increase the chances of success, such as the purity of starting materials, the existence of oxygen, particle size, heating and cooling rates, the size/shape of containers, and so on.
As for the infighting of the Korean team, we can't blame them for being too excited and even making the scene very chaotic for a time. Lowe said that if he discovered the room temperature superconductor, he would be equally excited to find his head.
On the whole, the expert showed cautious optimism after reading these two papers:
The calculation results of China Academy of Sciences and Lawrence Berkeley are very positive progress, and the video released by Huazhong University of Science and Technology on social media is by far the most credible presentation of room temperature superconductivity in the world, and the next few days and weeks will be very interesting.
And the prospect of this material is self-evident: "If it is confirmed, then anything that uses electromagnetism can be improved according to the current density it can carry. 」
LK-99 testing Committee has been established in Korea.
According to Korean media reports forwarded by netizens, relevant Korean institutions have made preparations in many aspects to further confirm and develop LK-99.
First of all, South Korea announced the establishment of the LK-99 Testing Committee yesterday, hoping that the Q-Center team can provide a batch of new samples for testing.
At the same time, some media reported that South Korea has approved the patent of LK-99.
In addition, the Korean media also reported that before the publication of the paper, the Korean team reached a cooperation agreement with some Korean institutions on room temperature superconducting substances.
Team overview
Now, even the Wikipedia of LK-99 is updating the global reproduction progress of room temperature superconductivity in real time.
Teams from each country are also listed in detail.
Up to now, at least six teams in China have been trying to reproduce LK-99, and at least two teams are doing theoretical research.
References:
https://arxiv.org/pdf/2308.00676.pdf
https://www.zhihu.com/question/615350352/answer/3147641567
https://www.science.org/content/blog-post/room-temperature-superconductor-new-developments
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