Volume 1 Chaos Comes Chapter 15 Laboratory
The graduate office is on the third floor of the Science Building. This building is very different from the old Physics Building in both appearance and interior decoration. Its top view is in the shape of a Chinese character “回”, and it looks square from the outside. The inside facade has a huge glass curtain wall, and below it is a small garden with grass and dwarf trees, giving the overall look a very transparent feel.
After sending the email over the weekend, my teacher asked me to find a doctoral student in his laboratory named Kou Fubo. When I arrived at the door of the office, Kou was already waiting there. When he saw me, he greeted me very warmly.
"Fang Cheng, right? Welcome, welcome!"
This doctoral student was of medium height, slightly fat, with slightly curly hair like mine, but his face was clean-shaven. When we first met, he was wearing a plaid shirt and jeans, and he looked neat, though not glamorous.
"Teacher Gu told me that you are the best student in your class, just like that girl."
Teacher Gu, whose full name is Gu Tiepeng, is another great figure in the Department of Physics. He studies condensed matter physics. The so-called condensed matter physics is roughly the subject of studying the properties of all solids and liquids, and magnetism is of course one of its directions.
"Hello, senior. I brought some of our specialty grilled fish fillets, which can be shared with the students in the group." After all, I have a lot to learn from him, and I want to leave a good impression.
"Hey, you brought a gift, just leave it at the door of the office so that we can all enjoy it together. Do you have any plans for today? Or should I show you the equipment?"
"Undergraduates don't have any plans..."
No, she probably would have.
"When the girl joined the team, she already had work to do. Teacher Gu was very surprised. Of course, it's normal for her to have no ideas. She's still young."
I followed him through the brightly lit corridor, through the glass walls of spring.
"Is she testing that phenomenon called self-organization?"
"You know. She said she was verifying a theory, so she wanted to collect some data herself. In fact, she could have just handed the experiment over to us and then concentrated on deriving the formula."
The image of that girl's eyes shining when she was taking a very boring ordinary physics experiment class came to my mind. Wouldn't it be like asking her to die if she was not allowed to do it herself?
"This room is the magnetron sputtering laboratory."
We walked into a room inside, which was completely separated from the corridor by two walls. Through the two windows on the wall, we could see the instruments running inside, but we couldn't hear any sound they made.
"Let's go in and take a look. There's not many people inside now."
"Can we just go in... without wearing a white coat?"
"You don't need to wear it if you just want to operate the sputtering table. This instrument works fully automatically. You just need to push the sample substrate in."
I recall that in some works, the authors imagined that scientific researchers, regardless of their profession, must wear white coats 24 hours a day, but their lower bodies were wearing short skirts and stockings that absolutely did not comply with safety regulations, and their hair was disheveled in the laboratory. This was too funny.
Of course, the author who designed it like that may not understand scientific research, but he must understand the market very well.
We visited the sputtering station, clean room (we didn't go in), wire bonding machine, laser laboratory and microwave laboratory in turn. The laboratory building was quiet and busy on Monday. I was embarrassed to disturb the people who were working, so I listened and took notes quietly.
"In short, the process is like this: first, we use a sputtering table to grow flat magnetic materials, then we etch the desired shape and structure in the clean room, and then we use a wire bonding machine to bond aluminum wires for external circuits, and finally we can send them to various laboratories for measurement."
Ai Bishui did not appear in the places we visited before. Maybe she is not here today.
"Oh yeah, there's still one room left. Come back to the third floor with me."
It was a small cubicle next to the graduate student office, but there was a very long nameplate on the door.
Magneto-optic Kerr Effect Laboratory
"This is the Magneto-Optical Kerr Laboratory, which we call the MOKE Room for short." My senior brother said to me as he stood at the door. "Come in. This room is a little messy. After all, it's hard to keep it clean all the time when people are working there all the time."
The principle of entropy increase.
The room was about the size of a small bedroom, with an iron test bench and a wooden desk placed against the wall, and an old computer chair in front of the desk. In the center of the room was a heavy optical platform used to isolate vibrations, on which stood a half-meter-high special optical microscope. On the stage of the microscope was the test sample, and the wires from the sample spread out in all directions in the room, connecting to various instruments.
This place is definitely not "a little messy". There are all kinds of sundries on the test bench, table and floor: screws and nuts of various shapes, sample boxes of different sizes, insulating gloves piled up in a mess, speakers covered with dust, monitors and computer hosts thrown like garbage, as well as voltage and current sources and lock-in amplifiers stacked on the shelves against the wall...
But I immediately saw Ai Bishui with her hair tied up in the middle of the pile of junk. She was wearing a simple turquoise sweatshirt on her upper body and light blue slim jeans on her lower body. She was sitting at the table facing the window, typing attentively, just like in the classroom.
The sunlight once again shines impartially on her, and this composition reminds me of elves in the forest.
"Bishui, you're here. Can you introduce Fang Cheng to her? You know this place better than I do."
My brain had a violent stress reaction to this affectionate name.
"My wife just called me and said something happened to my baby, so I have to leave now."
The stress response disappeared. This senior brother got married so early...
Ai Bishui turned her head, gave a polite smile, and waved hello to her senior brother.
"Do you guys just call each other by their first names?"
"Isn't it always like this? My senior went abroad for a visiting scholar program before, and everyone in the group just called each other by their names. Well... Chinese people might feel a little embarrassed." Indeed, he was not Japanese, so there was nothing wrong with calling each other by their names.
"But what brought you to this lab?"
Ai Bishui said as she walked towards the microscope in the middle, and I moved over too.
"Isn't this... something you told me years ago? I just feel a little curious."
She would obviously ask this question, and fortunately there is a standard answer.
"Well... let me tell you about this big microscope. It's called a magneto-optical Kerr microscope. We call it MOKE image for short."
As she spoke, she walked to the middle of the pile of iron boxes and turned on a button that looked like a power button. The display screen on the optical platform showed some black and white shapes of varying shades.
"This screen shows a real-time image from the microscope, so you don't need to look through the eyepiece."
She put on the insulating gloves on the table and expertly turned a few knobs and switches, and the machine began to hum.
"That's the sound of circulating cooling water."
The white patch on the display expanded and deformed, swallowing up the black territory.
"We talked about this during dinner. Magnetic materials have structures inside. You can think of a large magnet as having many small magnets with north and south poles inside. They are called spins."
I recalled the conversation we had years ago, but my memory has long since become blurred.
"In fact, the number of spins is very large, and the structures that can be formed are very complex." She pointed to the display screen with one hand.
"These different shades of color are spins with different orientations, which represent different local magnetic fields. The effect of converting this orientation into color is called the Kerr effect."
As she spoke, she began to rotate the button of the current source, and the colors on the screen changed alternately from black to white depending on the direction she rotated.
"I changed the magnetic properties of the material by changing the current passed through it, and this change was visually displayed on the screen through the Kerr effect."
"That means we can observe the rotation and interaction of the spins from here in real time."
Similar to how infrared night vision goggles convert heat into visible light, Kerr microscopes convert magnetic fields into visible light.
"You can think of it that way, but the actual spin is smaller than a pixel on the screen."
She probably thought the demonstration was over, so she shut down the instrument according to the operating procedures and finally turned off the water cooling cycle.
"Oh, this house is such a mess."
I saw several large coils , some of which were bare and some were enameled wires. They were probably put here because they couldn't fit on the table. My senior told me that copper wire is mainly used to wind coils.
"By the way, senior brother said that some places cannot be moved, such as here." I followed her finger and saw a palm-sized piece of metal.
"This is a piece of neodymium iron boron, the most powerful permanent magnet in the world. If your finger is pinched by it, it may break a bone."
As she said this, she picked up the wrench and hit it hard, but it didn't move at all.
"And there's the electromagnet on the ground."
There is a one-meter-high circular electromagnet placed on the ground. It generates a magnetic field by passing current through a disc-shaped copper wire.
"You can't touch this electromagnet because... it's old and not very strong. It might fall apart."
