Chapter 148 It’s so stupid to compete with Ning Chen
Ning Chen thought for a while and said:
“I think we can try adding some atomic-scale impurities first. Impurities of this size , which is more conducive to guiding the elastic ejection of quasiparticles."
Hearing Ning Chen's words, Qi Wan also nodded and said:
"Yes, atomic-scale impurities are the most suitable. And I think adding one or a few atoms is enough. Let’s screen out the types of atoms that can be selected, and then try them one by one.”
Ning Chen and Qi Wan discussed it for a while, and both felt that adding metal atoms was the most suitable.
Adding metal atoms to the sample can cause chemical adsorption between them, thereby changing the electronic structure of the sample.
In this way, the signal of the scanning tunneling microscope can be affected, thereby narrowing the energy gap and generating new electronic states.
......
In the following days, Ning Chen and Qi Wan tried to add various metal atoms as impurities to the sample and observed that after adding the impurities, the scanning tunneling microscope received changes to the information received.
As Ning Chen predicted before, after adding impurities to the sample, the STM imaging did have some changes compared to before.
In these images, standing wave images similar to ripples in water appear.
Of course, a lot of the image information does not have particularly great use value. Ning Chen and Qi Wan are also constantly changing the types of impurities, striving to find the most suitable impurities to add.
The workload of the entire experiment is still very large, because each measurement requires a long period of debugging, and the addition of atoms requires low-temperature deposition, which is not very easy to operate.
However, after days of experiments, Ning Chen and Qi Wan finally found the most suitable impurity to add.
They found that when a small amount of Ag atoms were added to the sample Bi2Te3, the sample could exhibit a structure similar to a trimer.
This is very helpful for observing electron standing waves in the surface states of topological insulators.
The next time Ren Mingshan came to the laboratory to check the progress of the experiment, Qi Wan told Ren Mingshan about their latest experimental methods and the progress of the experimental subjects during this period.
After learning about the latest experimental progress, Ren Mingshan also nodded and said:
"Yes, this method of adding impurities to the sample is very clever. It can make the relationship between impurity atoms and sample atoms The replacement is carried out at intervals, thereby causing the electron interference effect. In this way, clear electron interference fringes can be produced. ”
This time, Ren Mingshan did not criticize Qi Wan like last time. After all, at this stage, there was really nothing to criticize about the experimental work done by Qi Wan.
Qi Wan was not happy because of Ren Mingshan's praise. After all, this method was proposed by Ning Chen.
As long as Ren Mingshan did not criticize himself, Qi Wan felt that he had escaped.
At this time, Ren Mingshan suddenly thought of something and asked Qi Wan and Ning Chen:
"Who came up with the idea of adding impurity atoms to the sample?"< br>
Hearing Ren Mingshan's question, Ning Chen was not in a hurry to answer.
After a brief hesitation, Qi Wan said:
"Teacher Ren, it was Ning Chen who suggested it."
Qi Wan knew clearly in her heart that she said so If so, he might be criticized by Ren Mingshan again, or Qi Wan might be asked to continue learning from Ning Chen.
However, Qi Wan still feels that he should tell the truth. This is the most basic bottom line for Qi Wan as a person.
This time, Ren Mingshan did not criticize Qi Wan for this, but said approvingly to Ning Chen:
"As expected of a student who can publish so many articles in Nature at such a young age, his scientific research ability is really great." Stronger.”
Ning Chen is not a physics major, but he has made such great progress in less than a month after entering the laboratory. Ren Mingshan can only express his admiration for this. .
"Teacher Ren received the award. Many of the ideas were proposed by Qi Wan, and I just helped Qi Wan with some auxiliary work."
Ning Chen naturally couldn't put it down. His own contribution is too high, and of course this kind of recognition from Qi Wan is also sincere.
"Well, Qi Wan did a good job this time. You two performed very well."
Seeing what Ren Mingshan said, Qi Wan finally found some psychological balance.
After learning about the progress of this topic, Ren Mingshan did not leave immediately.
"By the way, let me tell you two something. I plan to apply for a project recently, which is to study the relationship between topological superconductors and Majorana fermions. After the previous project is completed, we will almost We can start a new topic." Qi Wan and Ning Chen were both very interested when they heard about the new topic.
Although Qi Wan doesn't like Ren Mingshan criticizing herself, this will not change Qi Wan's love for physics.
Qi Wan also knew in her heart that Ren Mingshan was strict with herself for her own good, but sometimes, Qi Wan needed some time to calm down her mood.
Ning Chen had already prepared to study Majorana fermions, but Ning Chen did not expect that Ren Mingshan did not choose iron-based superconductors as the research object, but chose topological superconductors. .
Ren Mingshan gave his reasons before Ning Chen asked.
"Ning Chen, your previous small paper on iron-based superconductors and Majorana fermions is actually of high research significance. However, I am not good at iron-based superconductors. Moreover, topological superconductors are easier to observe, so I decided to study this direction better.”
After listening to Ren Mingshan's explanation, Ning Chen also felt that this reason was very reasonable.
Although the theory in my previous small paper was very complete, if Ning Chen really wanted to explore it through experiments, he would probably not get any results.
Because of its own characteristics, topological superconductors will form a special state, that is, topological phase, at low temperatures.
In such a state, the number of states that electrons can present on the Fermi surface is much more than that of conventional superconductors, and it is easier to observe various valuable phenomena.
Ren Mingshan explained his general idea to Ning Chen and Qi Wan. After listening to it, Ning Chen and Qi Wan both felt that the whole plan was very feasible.
"Ning Chen, I have to thank you for your previous small paper on iron-based superconductivity and Majorana fermions, which gave me a lot of important inspiration. I didn't expect that teachers can also learn a lot by assigning homework to students. Something."
Ren Mingshan's words were so heavy that Ning Chen didn't know how to answer them, so he had to keep a polite smile.
After Ren Mingshan left, Qi Wan quickly asked Ning Chen:
"What is that little paper that Teacher Ren mentioned?"
Just now Ren When Mingshan said this, Qi Wan was very curious about it.
However, Qi Wan did not dare to ask more questions when Ren Mingshan was present, so she had to wait until Ren Mingshan left to ask Ning Chen.
“Oh, during my previous teacher’s quantum physics class, Teacher Ren once left an assignment asking to discuss whether Majorana fermions exist, and then I wrote a short paper. Hand it over..."
Listening to Ning Chen's explanation, Qi Wan finally understood the cause and effect.
"I see, no wonder Teacher Ren invited you into the laboratory. I thought it was arranged by the school before."
"Well, originally Yanda would also arrange for me to enter the laboratory. , but Teacher Ren gave me a chance in advance, so I came here.”
Thinking about it this way, Ning Chen completely relied on his own strength to attract Ren Mingshan's attention.
Qi Wan suddenly felt that it was very stupid for her to secretly compete with Ning Chen before.
Ning Chen has obviously published several papers in "Nature" and has already made achievements in the field of scientific research.
Even if physics is not Ning Chen's strong point, there are still many similarities between physics and materials science.
Qi Wan is just a rookie who has just been in the laboratory for a few months and has nothing to show off at all.
Seeing that Qi Wan's expression seemed a little lonely, Ning Chen felt that Qi Wan might still have some opinions about Ren Mingshan, so he persuaded him:
"Qi Wan, actually I can see that Teacher Ren pays special attention to you. . Maybe he has very high expectations for you, so he is so strict with you."
Normally, Qi Wan is only a freshman or sophomore at this age, but Qi Wan has already completed it. Undergraduate studies directly enter the doctoral stage.
Even compared to Lin You and Song Xiyun, Qi Wan has a higher talent.
“Well, I understand this in my heart. Okay, let’s not say so much. Let’s finish this topic quickly, and then prepare for a new topic.”
(End of this chapter)