Chapter 341 152K High Temperature Superconductivity!
After sending Gao Hongming away, Xu Chuan called Peng Hongxi again. After briefly explaining and arranging the test of the mathematical model, he plunged into the study again.
Although the copper-carbon-silver composite superconducting material developed by the Chuanhai Institute of Materials is a low-temperature superconductor, he found a glimmer of light leading to the mechanism of high-temperature superconductivity.
Compared with going to Gucheng to verify the mathematical model of ultra-high temperature and high pressure plasma turbulence, the significance of this theoretical work can be said to be more important.
At least in his own opinion, the importance is even higher.
It can be said that there are many people who can replace him in the verification of mathematical models of plasma turbulence, but it can be said that there are almost no people who can replace him in the work of searching for the superconducting mechanism of high-temperature superconducting materials.
Even if his mentor Witten came, he could not use mathematical language to explain the superconducting energy gap of superconducting materials.
This is no longer a problem that can be solved by pure mathematical ability.
No matter how strong your mathematical ability is, if you don't understand the basic characteristics of materials, if you don't understand the various properties of high-temperature superconducting materials, and if you don't understand the inherent characteristics and derived characteristics of materials, it will be impossible to make it.
In his previous life, he was unable to find the superconducting mechanism of high-temperature superconducting materials. On the one hand, he did not invest time in it.
At that time, he thought that it would be enough to get the superconducting material out. As for the mechanism, if he didn't study it, someone would study it, so it didn't matter.
On the other hand, his mathematical ability in his previous life was far inferior to that in this life.
In his previous life, he won the Fields Medal incidentally for solving the gap between Yang Mills' existence and quality.
His mathematical abilities are indeed among the best in terms of partial differential equations, nonlinear equations, calculation functions, etc., but mathematics is not just about these.
Algebra, number theory, geometry, calculus, topology, functional analysis, and probability theory. All in all, there are more than twenty major categories of mathematics.
And under each major category, there are numerous subcategories. For example, under algebra, there are linear algebra, group theory, field theory, Lie groups, Lie algebras, Kac-Moody algebra, ring theory, and more than a dozen different fields.
Not to mention his previous life, even in this life, he dare not say that he understands all fields in mathematics.
In the study, Xu Chuan continued to improve the superconducting mechanism of superconducting materials while sorting out the data about superconducting materials brought back from Chuanhai Laboratory.
Judging from current research, superconducting states are the product of electrons forming Ku-Bo pairs and then condensing. The core issue of the superconducting mechanism is the formation of electron-Kubonic pairs.
The superconductivity in cuprate superconductors is generally assumed by the CuO2 plane, and the nearby carrier library layer plays a role in adjusting the physical properties of the CuO2 plane.
However, due to the strong correlation characteristics of electrons, the physical properties of CuO2 cannot be described by the existing solid energy band theory.
So he needed to make a new mathematical description of solid energy generation theory.
In front of the desk, Xu Chuan stared at the data on the computer screen, his eyes bright, and murmured to himself:
"Figure 1a shows the structure of the BiO surface exposed after the dissociation of the Bi2212 single crystal sample. It can be seen that there is an incommensurate modulation structure along one direction."
"In high-temperature superconductors, the originally continuous closed Fermi surface calculated by the energy band theory does not appear. Due to the strong correlation effect, the Fermi surface becomes four Fermi arcs, with a high density of states at the end points of the Fermi arcs."
"So there are 7 scattering wave vectors between the 8 endpoints, which are described by q1...q7 respectively. After measuring the pattern formed by quasi-particle coherent scattering, Fourier transform can be used to obtain the values of these 7 wave vectors Scattered bright spots.”
"This can be screened using Phase-Referenced Quasi-Particle Coherent Scattering (PR-QPI) technology. This can outline the information of the Fermi surface in q-space."
"However, in fact, this physical quantity is a complex variable at any q point and has a phase, that is, r(q, E)=|r0(q, E)|exp[ij(q, E)]"
In front of the computer, Xu Chuan analyzed the data of copper-carbon-silver composite materials in his mind, and refined his theories and ideas in his mind.
Unlike mathematical arguments, the exploration of materials physics does not require long mathematical calculations.
Mathematics only plays a key foundational role in this process. More importantly, it is how to explain related phenomena through a complete set of theories.
This is actually somewhat similar to theoretical physics. Just like when Einstein first proposed the theory of relativity, he first gave the initial form of general relativity and then improved it bit by bit.
In the process of perfecting the theory of relativity, mathematical tools were used to confirm it bit by bit through the gravitational field equations, Mach principle, space-time diagrams, etc.
This is probably the commonality of all natural subjects. In the end, the research must be attributed to the commonality of mathematics.
If a theory cannot be logically consistent or verified mathematically, then no matter how perfect the theory is, it may only be a flash in the pan.
"Perhaps I have found a suitable path!"
Looking at the images and data on the computer, Xu Chuan's eyes became deeper and deeper, like a vast ocean, containing countless knowledge.
Quickly taking out a new stack of manuscript paper from the drawer, he picked up his pen and began to deduce.
“rr(q, -E)=|r(q, -E)|cos[j(q, -E)-j(q, -E)]”
“The physical quantity of the phase reference calculated based on the experimental data, each dotted circle indicates the position of the 7 scattering spots and the area of the intensity integration. It can be seen that in the case of d-wave energy gap, q1, q4, q5 correspond to the energy gap with the same sign”
“The QPI intensity of the phase reference rr(q, -E)=|r(q, -E)| cos[j(q, -E)-j(q, -E)]. (d), (e) and (f) show the integral of the rr(q, -E) intensity in the dotted circle, q2, q3, q6, q7 corresponds to the energy gap anti-sign scattering."
"In this model, if only the square lattice formed by the copper lattice is considered, i and j are the indicators of the copper lattice, and in theory, ci and σ are usually regarded as electron annihilation operators in a general sense, then."
The black signature pen wrote one by one on the white A4 paper.
With the calculation of the energy gap data and phase physics of copper-carbon-silver superconducting materials, Xu Chuan's eyes became calmer.
Finally, he stopped writing and looked at the last line of equations on the manuscript paper.
【S→=C〃σc】
"So that's it. The energy gap in superconductors is d-wave symmetric, at least in copper-carbon-silver composite superconducting materials."
"The energy gap can be obtained using single-band Hubbard mathematics and Gutzwiller projection operators. Although this method is not used in all cases, the low-energy effective theory under strong coupling is basically the same."
"If the theory of similar models such as the t-J model and the renormalized mean field method are used to treat high-temperature superconducting materials, the Gutzwiller approximate renormalization factor can be used first, and the second step is to use the standard mean field method for further processing."
"In this way, the superconducting energy gap of high-temperature superconducting materials can be deduced step by step through experimental data."
"And this method is expected to become a powerful means to determine the sign reversal of the energy gap function in other unconventional superconductors."
"Perhaps in the near future, high-temperature superconductivity will usher in a booming development."
Looking at the theory and formulas on the manuscript, Xu Chuan let out a long breath.
By freeing up time to go to Gucheng to verify the mathematical model of plasma turbulence, he has preliminarily figured out the superconducting mechanism characteristics of high-temperature superconducting materials.
The rest is to find more data on high-temperature superconducting materials to verify this theory.
After standing up and stretching his muscles, Xu Chuan sat back at his desk.
After tidying up the manuscript, he began to transfer the contents on the manuscript to the computer bit by bit to write a paper.
Of course, this paper is impossible to make public at present.
Although the research on the superconducting mechanism characteristics of high-temperature superconducting materials is one of the hottest fields in the superconducting materials industry today, his paper may instantly detonate this pond and make him a top bull in the superconducting materials industry.
But correspondingly, this will also point out a way for others to study high-temperature superconducting materials.
So this paper can only be hidden in his hands for now.
But Xu Chuan didn't care too much.
It won't be too late to publish it after he makes the high-temperature superconducting material.
After sorting out the paper on the manuscript and entering it into the computer, Xu Chuan got up and went straight to the Chuanhai Materials Laboratory.
He has already figured out the superconducting mechanism characteristics of high-temperature superconducting materials. If he wants to use them, it is best to establish a strongly correlated tj model for calculation.
However, it takes at least half a month to build a model and test it, even the most basic and crude version.
He can't wait any longer. He wants to go to the laboratory to test and see if he can make further optimization on the superconducting materials based on the data and theory he calculated.
After rushing to the Chuanhai Materials Research Institute, Xu Chuan found Fan Pengyue and asked him to arrange a laboratory for him.
The institute didn't have any extra laboratories. After all, it was less than two months after the expansion, and the recruited personnel and purchased equipment were not very complete.
In addition, he had previously required a lot of research on superconducting materials and carbon-based materials, and now it is already at full capacity.
However, Song Wenbo, who had previously studied copper-carbon-silver composite materials, was arranged to analyze materials, and the laboratory he originally used was temporarily vacant, which was just right for him to use.
In the laboratory, Xu Chuan personally controlled the vacuum metallurgical equipment to manufacture copper-carbon-silver composite materials.
Compared with other nano-manufacturing methods such as physical crushing, mechanical ball milling, and vapor deposition, the use of vacuum evaporation, heating, high-frequency induction, and other methods to vaporize or form particles, and then quench, can obtain raw materials with high purity, good crystal organization, and controllable particle size.
Perfect crystallization and uniform particle size are very important in the manufacture of materials, especially in the study of materials in the laboratory.
Of course, there are also disadvantages. This method of preparing nanomaterials requires high equipment and preparation technology.
However, things that can be solved with money are not a big deal in Xu Chuan's eyes.
On the side, Fan Pengyue and Song Wenbo were helping in the laboratory.
Of course, they were also a little curious about what this person was going to study, or how to prepare copper-carbon-silver composite nanomaterials.
Before Xu Chuan got the data of Song Wenbo's ultra-low temperature copper-carbon-silver composite superconducting materials, it was obvious that he went to study them.
In just ten days, he could find some discoveries or inspirations from them?
Neither of them dared to think about deeper things.
They all thought that Xu Chuan had found some clues to the possible optimization of copper-carbon-silver composite materials by studying the data of ultra-low temperature copper-carbon-silver composite superconducting materials.
To be honest, this is already amazing.
After all, the time is so short, and the data on materials is not so easy to analyze.
As for finding the superconducting mechanism behind high-temperature superconducting materials through these data, the two of them have never thought about it.
If the superconducting mechanism of high-temperature superconducting materials is so easy to study, it would not be that iron-based, copper-based, graphene and other high-temperature superconducting materials have come out now, but the mechanism has not been found.
In the laboratory, Xu Chuan wore a white coat, a protective mask and goggles, and carefully controlled the RF magnetron sputtering equipment with full concentration to sputter the prepared nanomaterials on the SrTiO3 substrate.
This step takes about two minutes to allow the nanomaterial to completely cover the SrTiO3 substrate and form a thin film on it.
Then add 2% (volume fraction) of multi-walled carbon nanotubes (CNTs) and carbon nanotubes modified by surface Cu plating as reinforcement phases.
After a series of treatments, it is finally protected by inert gas and heat treated at a temperature of 860℃-900℃ for 30-50 minutes to form a copper-carbon-silver composite film on the SrTiO3 base.
And this film is what Xu Chuan needs!
After staying in the laboratory for two full days, Xu Chuan's tense nerves did not relax until late at night the next day.
In the vessel in his hand, a silver-gray film less than the size of a child's palm was lying there quietly. This is the result of his two days of busy work.
With a long sigh, Xu Chuan handed the transparent vessel in his hand to Song Wenbo and said, "Please test the superconducting mechanism of this material, Professor Song."
"If my calculation is correct, it should reach the critical Tc at around 152K."
After a day of concentrating on it, he really didn't have the energy to do the test, so he could only hand it over to others.
Hearing this, Song Wenbo opened his mouth and hesitated, and finally nodded and took the material.
It is not difficult to test superconducting materials. It can be done through equipment such as low-temperature thermostats and Dewar liquid nitrogen containers.
It's just that he doesn't believe this person's critical Tc of 152K.
What is the concept of critical Tc of 152K?
Converted to degrees Celsius, it is about -121.15℃. This temperature sounds very low, but it is very high in the current superconducting material industry.
Putting aside those superconducting materials that require high pressure conditions, the current copper-based high-temperature superconductor can reach a superconducting temperature of 94.9K, and can reach 125K under pressure, which is about -178.2℃ and -148.15℃ in Celsius.
The temperature difference is 30℃. Don't underestimate this point. You should know that the critical temperature of copper-based high-temperature superconducting materials has not been broken through for almost ten years.
As for iron-based superconductors, although the limit can reach -23℃ superconductivity, it can only be manufactured in a very small number in the laboratory at a great cost.
Not to mention the small quantity, it is also very easy to be contaminated. If it is exposed to the air casually, it will cause superconductivity to fail, so there is not much comparison value.
And if the film in his hand can really achieve superconductivity at a temperature of 152K, the high-temperature superconducting industry will probably usher in earth-shaking changes.
More importantly, his boss has calculated this number in advance.
He no longer dares to think about the meaning of this.