Academician of CAS Mr. Dou Youwei: Progress of Magnetic Materials

The earth has a large magnetic field, which is the protective layer of the earth. Without this magnetic field, the high energy magnetism of the universe would constantly disturb the earth, making the biosphere of the earth unable to exist.

First and foremost are the basic concepts of magnetic material. Magnetic material is a basic functional material. From the perspective of industry development of human history, the first industrial revolution relied on the steam engine; the second industrial revolution relied on the electric generator, motor. Since power is generated by changing the magnetic field, so the second industrial revolution is closely related with magnetic electricity. The third industrial revolution is mainly based on computers and atomic energy, which shows that it has nothing to do with magnetism, but the storage of information depends on the disk, and a variety of soft magnetic materials and permanent magnets are used in the industrial field. The fourth industrial revolution is dominated by nanotechnology, including nano magnetic materials.

Why should we attach importance to the industrial revolution? Because almost every 100 years of industrial revolution is the opportunity to reshuffle the cards. Seize the opportunity of the industrial revolution, for it may turn those backward countries into advanced ones. In 1970s, those countries who attached significant importance to microelectronic technology have now become developed countries. Countries that attach importance to nanotechnology now are likely to become advanced nations in the next century. , President Xi Jinping stressed innovation in his two academicians' reports, suggesting that science and technology are the basis of national innovation and that innovation is the spirit of national progress. Science and technology is the weapon of the country, which a country relies on to strengthen its power, enterprises rely on to thrive, and people relies on to prosper.

Those who seize the industrial revolution, rely on innovation, and get out of the crisis are winners. China Manufacturing 2025, and even China Manufacturing2050 are under planning, these are related to the magnetic. The Internet, big data, cloud computing need to store data, and on what the data storage relies? The disk that we used to rely on is now dying out of the age. What is the chip for Post Moore Era? It's probably magnetic material.

Magnetism is generally divided into three categories, the first category is the permanent magnet materials, second one is soft magnetic materials, and magnetic material is third. The original disk will be eliminated later and become a solid state storage system, and the permanent magnetic output now used on disk will be reduced immediately. We should seize this opportunity to build the chip market in China. The chip is the heart of modernization, and we must control it. Otherwise, once the core imported from abroad breaks down, our “heart” will stop beating. This is a big opportunity, magnet materials are gaining great momentum in foreign countries while China is left behind.

In 2014, China's rare earth permanent magnet production was120 thousand tons, surpasses 85% of the world production volume, foreign countries can not compete with us. But we can't go through their patent barriers. The significance of this statistic is that if the amount of magnetic material per capita is greater than the average, it means that you are a developed country, and if you are below average, you are less developed or developing.

Hysteresis Loop Characterization of magnetic materials are mainly permanent magnetic, soft magnetic and magnetic records, and now I mainly talk about permanent and soft magnetic.

The main material of permanent magnet is carbon steel, ferrite and rare earth permanent magnet. Production of major permanent magnetic materials in the world is increasing. Now there is a new development of the permanent magnet is the soft magnetic composite permanent magnet two, which in many aspects of the new achievements. The highest performance theory of rare earth permanent magnet is up to 93%. After three generations, great progress has been made. At present, the fourth generation of permanent magnet has not been developed. Application of permanent magnet motor is very wide, usually we use the car more than 30 to be used in magnetic materials, the more that the higher the level of automation of car, we sat very comfortable, but you don't know what this is to bring comfortable magnetic materials. In addition, the wind power generation is also using permanent magnet generator, and the wind turbine 3MW needs 1.5 tons of rare earth permanent magnet.

Soft magnetic. All communications need to use soft magnetic material, from low frequency to high frequency, the whole spectrum should use soft magnetic material. The surface of the particle is coated with organic and inorganic adhesive. By the nanometer stage, its performance has been greatly improved. Iron soft magnetic materials, the first is the last century, Japan made out of the basic characteristics of the iron core, the DC bias characteristics, high saturation magnetic induction strength, permeability frequency characteristics of good linearity. Nanoparticles can even be made to frequencies of several megahertz. In general, low density to high density, usually we are using the flash, flash is cheaper, but the performance is not stable. After 1980s, the computer performance is greatly improved, the main reason lies in the head to read out signals, now with a serrated resistance effect, this is the first European discovery, and get the Nobel prize in physics in 2007.

Magnetic material with cross coupling effect. Among them, there are metamaterials, high-temperature magnetic refrigeration materials, spintronics and so on. Magnetism is closely related to biology and chemistry. Magnetic material is a kind of material with a wide range of applications. Effect of magnetic field on small animal such as, after the mice were injected the virus, found after therapy but without therapy after alive and kicking, died. Magnetism and biology are worth studying very much, now go to the hospital, be afraid of an operation first, second be afraid of chemotherapy, future magnetism machine is worth to have a try.

Now I'd like to introduce spintronics. French scientist Albert Phil and German scientist Peter Greenberger jointly won the 2007 Nobel prize in physics for their independent discovery of giant magnetoresistance. The Nobel prize was awarded only to the original invention, and the original invention was discovered by accident. The Nobel prize won't be awarded for the by-product, and the product won no Nobel prize. Add a layer to the layers, these are very common materials, but the nano combination can make new things later.

Spintronics is not only related to magnetism, but also to semiconductors. It is not a magnetic semiconductor, hearing magnetic are afraid, but now want to use magnetic, how to make magnets to semiconductor inside, used to control the charge and power steering, now can control the magnetic rotation. There are two state electromagnetic upward, the computer can be used now, without magnetic field to control, can the magnetization current, in this way can become 0 and 1, can be used in the computer.

Moore's law will probably end in 2020, and today's semiconductor chips will last for some time, but they may shrink in the course of the future. Later, you can combine the disk with the chip, do not need to have a disk, a chip which can have a great capacity. The spin chip has roughly gone through three stages of development. The first stage is the magnetic field controlled by electric current recombination before 2006. After 2006, the polarization current was used to control the spin, STT-MRAM, spin and membrane parallel and perpendicular to the two. The third stage is the current research and development of power plant regulation spin MeRAM.

Foreign developments, in 2013, European A350 aircraft using spin chip control system, this year, IBM teamed up with Samsung Corp announced the mass production of STT-MARM chips. Tohoku University Japan expects global demand for MRAM to reach $90 billion by 2020. Semiconductor spin electron technology is likely to cause revolutionary changes in information technology and become the leading new generation of microelectronic technology in the future and create a new information era. The three functions of future computing, storage and communication will be integrated on a single chip to form a new chip with powerful, ultra high speed, low power consumption, and radiation resistance. Interdisciplinary development is the general trend in the future.