Chapter 443 The Hope of Miniaturizing Fusion Reactors
After getting the replica experiment data and superconducting test data of KL-66 material, Xu Chuan did not make it public immediately.
The Meissner effect has been confirmed to be non-existent in these three sets of control replica experiments. Unless the replica experiments conducted by other laboratory research institutions show completely different results, from this point of view, it is enough to preliminarily confirm that KL-66 material is not a room temperature superconductor.
However, Xu Chuan thinks that since he wants to do it, he should do it perfectly and make it convincing and impeccable.
After confirming that the Meissner effect does not exist, the remaining key point is to find out why this material can have an antimagnetic effect.
After all, whether it is the video sent by South Korea showing strong antimagnetic properties, or the second group of KL-66 material samples in his replica experiment, they all show strong antimagnetic properties and can float.
Explaining the principle in this regard is enough to hammer the room temperature superconducting characteristics of this new material.
Of course, the reason why he wants to study the mechanism in this regard is not just to make it perfect. It is also because this mechanism aroused his curiosity.
It has to be said that the strong antimagnetic mechanism shown on the KL-66 material developed by South Korea this time does have some problems.
Judging from the antimagnetic test data of the material No. 2 KL-66, the reason why it can show the ability to levitate is that some of the polycrystalline ceramic samples reproduced contain soft ferromagnetic components.
This is the core of its ability to levitate under the application of an external magnetic field.
However, what surprised Xu Chuan was that when the external magnetic field was applied to 5T, this soft ferromagnetic component was not saturated.
This means that this material has great potential in antimagnetism.
So even if the three sets of replica experiments did not observe the Meissner effect, he still retained his research interest in this material.
After all, there are still many application fields of strong antimagnetism, such as magnetic levitation, medical treatment, motors, etc. If a new strong antimagnetic material can be found, there may be a chance to replace the expensive superconducting materials originally needed in some fields.
Of course, for him, what interests him more is the principle behind this mechanism.
If the mechanism behind this anti-magnetism can be found and applied to the field of real superconducting materials, perhaps he can further improve the critical magnetic field of superconducting materials, and then further compress the volume of controlled nuclear fusion reactors.
This is the main reason why he is really interested in this material.
This material may allow him to find a way to miniaturize fusion reactors.
In the laboratory, Xu Chuan found a researcher to assist him in his work and conduct anti-magnetic tests and structural analysis on the No. 2 KL-66 material.
At the same time, the second wave of replication experiments on the KL-66 material was launched again.
However, unlike the first time, this replication was not to verify the superconductivity of the KL-66 material, but to target its anti-magnetic effect.
Xu Chuan needs to figure out what happened during the synthesis process, which led to a huge improvement in the soft magnetic effect of the polycrystalline ceramic sample in the No. 2 KL-66 material, and how the corresponding crystal structure, atomic substitution and other things were formed.
It is also necessary to figure out why the No. 1 and No. 3 KL-66 materials did not have such a strong anti-magnetic effect with the same synthesis steps.
Only after knowing these things and confirming the mechanism can we start the next step of work.
"Boss, the detailed magnetization measurement report results are out."
In the office, Chai Li hurried over with a test report.
"Let me see."
Xu Chuan quickly took the test report from the other party and read it carefully.
In physics, the magnetism of general materials can be divided into several types, such as paramagnetism, diamagneticism and ferromagnetism.
For example, ferromagnetic materials are materials placed in a magnetic field or lowered below a certain temperature, the materials are magnetized, a strong magnetic field is generated and the materials have clear magnetic poles, such as some materials containing elements such as iron, cobalt and nickel, and the magnetized materials can retain ferromagnetism.
Paramagnetic materials are materials placed in a magnetic field, and the materials are magnetized to generate a smaller magnetic field with the same direction as the original magnetic field and proportional to the original magnetic field, but it will disappear after the external magnetic field is removed.
As for diamagnetic materials, the materials are placed in a magnetic field, and the magnetic field generated inside the materials is opposite to the direction of the original magnetic field, which will weaken the total magnetic field.
Generally speaking, ferromagnetic materials placed in a magnetic field will be attracted by the original magnetic field, while diamagnetic materials will be repelled by the original magnetic field.
If you want to understand it simply, diamagnetism is when two magnets of the same polarity are put together, and then you use your hands to squeeze them hard.
The greater the force required to make them stick together, the higher the diamagnetism.
Although this is not accurate, it is relatively easy to understand and vivid.
According to the test report, the magnetic susceptibility of the No. 2 KL-66 material reached an astonishing -0.8225.
This value is already very high for a non-superconducting material.
For magnetism, the magnetic susceptibility of a vacuum is 1, which means that the magnetic field in the vacuum is consistent with the original magnetic field.
The magnetic susceptibility of ordinary diamagnetic materials is negative, but very close to 0. For example, water, some organic matter, a small amount of metal, etc. are all ordinary diamagnetic materials.
The magnetic susceptibility of a superconductor is -1, reaching the maximum value of diamagnetism. It is significantly different from ordinary diamagnetic materials and has 100% diamagnetism.
Therefore, superconductors will strongly repel external magnetic fields and can firmly bind magnetic flux lines, while ordinary antimagnetic materials only slightly repel external magnetic fields.
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The magnetic flux of 0.8225 is still a certain distance away from the magnetic susceptibility of superconducting materials -1.
But don't forget that the purity of the KL-66 material they synthesized is not high.
If the purity continues to be improved, it is not impossible for the magnetic susceptibility of this material to be infinitely close to that of superconductors or even to be fully increased.
"Interesting, when will the electron microscope structure be released?"
Putting down the report in his hand, Xu Chuan looked at Chai Li and asked.
"It's already being done, and it will take about 20 minutes." Chai Li replied respectfully.
Nodding, Xu Chuan said: "Okay, give me the report as soon as it is done."
The amazing magnetic susceptibility did arouse his interest, which also means that even if this material is not a superconductor, it has considerable potential in some aspects.
Chai Li nodded, turned and walked out of the office, and gently closed the door.
Sitting at the desk, Xu Chuan began to think.
From previous tests on KL-66 materials, he passed the two-band model of copper eg orbitals to determine the interaction value from the constrained random phase approximation (cRPA).
But no forced magnetism or orbital symmetry breaking was found in the electron holes of the material.
And the mechanism that plays a role in the stable insulating state and the impurity level in the band gap in two insulators using DFT+U: Cu-doped Pb10(PO4)6o and V-doped SrTiO3 doped transition metals.
So in theory, there are isolated impurity (flat) bands, regardless of the doping position. Then even under the best conditions for superconductivity, the fluctuations of spins and orbits are still too weak for superconductivity close to room temperature.
Because it is almost impossible to show superconductivity at room temperature.
But if diamagnetism is considered, the situation may be different.
In theory, the gap of the material will lead to two spin-polarized impurity bands in the position of doping different types in the same unit cell.
And weak ferromagnetism is possible due to the relatively non-localized unpaired spins in the valence band.
Further work should consider the possibility of further changes in stoichiometry, different doping positions, supercell effects, and quantification of magnetic exchange interactions.
In the office, Xu Chuan silently deduced in his mind, and occasionally took a pen to calculate on the manuscript paper.
The material science knowledge in his mind merged with the information in the fields of physics and chemistry.
If anyone has experienced the moment when he proved the last step of the NS equation in class before, he would be familiar with his state.
But at this time, there was only Xu Chuan in the office. With his full concentration on deduction, he did not realize that he had returned to the state he dreamed of today.
Until a long time passed, Chai Li, who came with the electron microscope structure data, called out softly, and Xu Chuan came back to his senses.
The illusion of being in another world made him breathe a sigh of relief. He looked at the time in the lower right corner of the computer and realized that nearly half an hour had passed without him realizing it.
"Boss, the electron microscope structure data is out." Chai Li swallowed his saliva and reported. Why did he feel like he had done something wrong when he had done nothing?
Xu Chuan nodded and said, "Just put it here."
"Okay." Quickly putting down the test report in his hand, Chai Li ran away. Originally, he had some questions to ask, but suddenly changed his mind.
Sitting at the desk, Xu Chuan closed his eyes and thought about it. After a while, he leaned forward and picked up the electron microscope scanning structure report from the table and flipped through it.
"Sure enough. At the non-interaction level, KLyl semimetal material."
"Weyl nodes with opposite chirality appear at points in the Γ and A three-dimensional Brillouin zones at different energies near the time reversal invariant. The unusual Weyl charge CW=±2 and connects the c-axis through two branches of the topologically protected Fermi arc state on the surface parallel to the main body."
"That is to say, in the KL-66 material, the spin-orbit coupling of Cu atoms has a crucial impact on the material's band structure and electronic properties."
Looking at the scanning structure diagram and related inspection data, Xu Chuan's eyes showed a look of long-awaited prediction.
Although his derivation was interrupted by Chai Li, he was not without gain.
Theoretically, he has roughly found the core reason why KL-66 material has strong magnetism through inference.
But whether it is accurate or not still depends on subsequent experiments.
Perhaps this time, he can make a complete connection between strong antimagnetic materials and band topology, and then push strong correlation physics to a whole new level.
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