The Chinese Academy of Sciences and others have discovered suspected new room-temperature superconducting materials, author: I am very confident in the results

Abundant color from the temple of Wafei

量子位 | 公众号 QbitAI

Room-temperature superconductivity is here again?

In the past two days, bigwigs from the Chinese Academy of Sciences, Beijing University of Science and Technology, South China University of Technology and other institutions (with the screen names "Really Cute Stupid, Teacher Xi, Guan Shankou, Fire Machine Immortal, Frog, Teacher Chen", etc.) released the latest joint research results:

Copper-coated lead-based apatite may have the Myinas effect (one of the superconducting features) near room temperature.

That is, it is suspected that there is another room-temperature superconducting material that becomes hopeful.

It is understood that the samples involved came from different units, different synthesis methods were used, and different laboratories and methods were used for testing, but the results obtained were highly uniform.

As soon as the news came out, everyone was boiling again. Related topics quickly ranked third in Zhihu's hot search.

Seeing that the war between the guide and the sending faction is about to break out, the author himself also responded one after another, so it was not lively.

This will take everyone to the first melon eating scene.

Copper-substituted lead-based apatite, the new room-temperature superconductivity?

Let's take a look at the main content of the paper first.

The main findings are as follows:

1. In copper lead-surdated apatite (CSLA) below room temperature, the authors observed diamagnetic DC magnetization at 25 Oe magnetic field and a significant bifurcation between zero-field cooling (ZFC) and field-cooled (FC) measurements.

(The bifurcation phenomenon indicates that it is similar to the typical magnetization data to the superbody)

2. When the magnetic field increases to 200 Oe, its properties become paramagnetic.

Then, during the cooling process, a glassy memory effect (an inflection point of about 100 K) appeared.

3. Below 250 K, a typical superconducting hysteresis loop (i.e., the diamond curve in figure d below, one of the hallmarks of standard superconducting materials, is less symmetrical because of the vitreous memory effect), and there is an asymmetry between the forward and backward scans of the magnetic field.

4. The author's final conclusion is:

Experiments have shown that the Meissner effect may be present in this material at room temperature.

This is the M-H hysteresis phenomenon they measured at room temperature.

Note that it is "possible", and the title of the paper also uses "possible" and "near", which shows that the author's attitude is more cautious and does not conclude that superconductivity is a thing.

Zhihu netizens @momo gave a relatively easy to understand summary:

Overall, this study investigates diamagnetism in CSLA, a phenomenon that can be observed at temperatures up to 250 K, through a dual study of the M-T curve and the hysteresis M-H loop. Given the zero-field cooling and field-cooled bifurcation above 300 K, the authors believe that there is still a good chance of observing superconductivity at room temperature.

However, the only problem is that the signal in the sample is very weak, and more scalable samples of the active ingredient need to be further synthesized and then further validated (the authors also mention this in the paper).

Zhihu netizen @芝了 (postdoctoral fellow in condensed matter physics at the Hong Kong University of Science and Technology) also pointed out:

The weak diamagnetic signal may be related to the small volume fraction of superconductivity, and it is necessary to rule out whether it is the diamagnetic background of the sample rod.

Professor Luo Tianyong of the School of Mechanical and Electrical Engineering, University of Electronic Science and Technology of China, also gave a summary and views.

Some netizens summarized it as a very easy-to-understand "baby with reading version":

To translate, Professor Luo said:

There are two technologies, EPR and squid (i.e., pregnancy test sticks), which confirm the near-room temperature superconducting phase of CSLA, but the critical magnetic field is really only so weak, and it will be difficult to apply.

In addition, what exactly causes the generation of superconducting phases in the copper-substituted lead-based apatite system has not been clarified, and further verification is needed.

There are many people who are optimistic about the whole discovery, and as for the doubts, of course, there are also doubts.

For example, Zhang Zili, an associate researcher at the Institute of Electrical Engineering of the Chinese Academy of Sciences, published a Zhihu article, saying:

Due to the mismatch of magnetic susceptibility data, it is not enough to express that one thousandth of a thousand is from the superconducting phase in such a weak signal.

In addition, he believes that the M-T curve also has the irrationality of "remanence", so he does not think that this is a valid proof of the Meissner effect, and it needs to be further proved.

The author personally responded: very confident in the test results

Under the topic of related Zhihu, several authors responded in person.

The first is "Xizhixi", that is, Professor Yao Yao of South China University of Technology, who first admitted that "the signal is indeed relatively poor, an order of magnitude smaller than South Korea's LK-99, and the superconducting volume fraction is about 5 thousandths."

In addition, he said that this was because the sample size was already small, and he also divided part of it to do EPR (microscopic magnetic measurement).

He expressed confidence in the test results, because the transition temperature and critical magnetic field can be cross-corroborated and self-consistent with the data of the microwave test.

The most important thing is that the samples come from different units, different synthesis methods, the tests are performed by different people in different laboratories, and the test methods are completely different, but the results obtained are highly uniform.

At the end, he also hung everyone's appetite:

In addition to the Minus effect in this article, there is something worthwhile and is already being arranged in a step-by-step manner.

As for what it is, judging from Mr. Xi's response to Zhang Zili's question, it may be a video.

The second is "really cute", TA shared the discovery process, and it seems that the whole discovery is mainly a coincidence.

In my words, it was mainly "the EPR test, the unique skill of the washing teacher, from the samples that were about to go to the trash can, and then I found Meissner".

Another writer with the online name "Fire Machine Immortals" added:

This paper explains why the Koreans tested the ZFC-FC at 25Oe.

And he thinks that both the high critical temperature and the low pressure are perfect, and the defect is obviously in the magnetic field.

After reading his explanation, netizens excitedly said that the flaws improved the authenticity of the study.

Finally, Chen Ning, a teacher of materials physics at the University of Science and Technology Beijing, said very sincerely:

For the controversy and strange phenomena in the research, all parties can fully express their own opinions, do not have to draw conclusions immediately, and can look at the new results of others.

And he argues:

Overall, this article is a milestone, but it is not a sign of the victory of the Steering School, but rather a starting point for a concerted effort to focus on the relationship between the structure and performance of such systems.

What do you think this time?

Address:

https://arxiv.org/abs/2401.00999

Reference Links:

https://www.zhihu.com/question/637763289

-ENDS-