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Nano-magnetic material application and development

Magnetic is the basic attribute of matter. Magnetic material is an old and widely used functional material. Nano magnetic material is a new type of magnetic material that has been gradually developed, developed and expanded since the 1970s, becoming the richest vitality and broad application prospect. One of the reasons that the U.S. government significantly increased funding for nanotechnology research this year was the high profit of magnetoelectricity in the huge market of devices and high technology. The giant magnetoresistance effect of the market for high density readout heads is estimated at US$1 billion. Currently, it has entered large-scale industrial production. The market for magnetic random access memory is estimated at 100 billion US dollars. It is expected that it will be put into production soon, and the application market for magnetic sensors is also very broad. Nano magnetic materials and applications can be broadly divided into three types: 1. Nanoparticles * Magnetic recording media * Magnetic liquids * Magnetic drugs * Absorbers 2, Nanocrystallines * Nanocrystalline permanent magnets * Nanocrystallines Soft Magnetic Materials 3, Nanostructured * Artificial Nanostructured Materials Films, Particle Films, Multilayer Films, Tunnel Junctions * Natural Nanostructured Materials Perovskite-type Compounds Nanomagnetic Properties Unlike conventional magnetic materials, the reason is associated The physical length associated with magnetic properties is exactly in the order of nanometers. For example, the magnetic monodomain size, the superparamagnetic critical dimension, the exchange length, and the mean free path of electrons are approximately in the order of 1-100 nm when the size of the magnetic body. When the physical length of these features is comparable, abnormal magnetic properties are exhibited. Magnetic materials are closely related to information technology, automation, mechatronics, national defense, and national economy. Magnetic recording materials are still the mainstay of the information industry. The magnetic recording industry has a production value of about 100 billion U.S. dollars. In order to increase the magnetic recording density, magnetic The size of the magnetic particles in the recording medium has gone from micron to submicron to nanoscale, for example, the size of the alloy magnetic powder is about 80 nm, the size of the barium ferrite magnetic powder is about 40 nm, and the direction of further development is the so-called “quantum disk”, which uses magnetic nanometers. The storage characteristics of the line, recording density is expected to reach 400Gb/in2, equivalent to 200,000 red squares per square inch can be stored, the limit of the magnetic recording density phase value determined by superparamagnetic about 6000Gb/in2. In recent years, the disk recording density has advanced by leaps and bounds, and now exceeds 10 Gb/in2. The most important reason is that it is applied to a giant magnetoresistance effect readout head, and the giant magnetoresistance effect is based on the spin-related loss of electrons in a magnetic nanostructure. Transport characteristics. The magnetic fluid was first used in the aerospace industry, and was later applied to the civil industry. This is a typical application of nanoparticles. It is composed of superparamagnetic nanoparticles coated with a surfactant and then dispersed in the base fluid. At present, the United States, Britain, Japan, Russia and other countries have magnetic liquid companies, magnetic liquids are widely used in rotary seals, such as disk drive dust seal, high vacuum rotary seal, and speakers, damping devices, magnetic printing and other applications. Magnetic nanoparticles as targeted drugs, cell separation and other medical applications are also a hot research topic in biomedicine, and some have entered clinical trials. 1967 SmCO5. The introduction of the first generation of rare earth permanent magnet materials set a new milestone in the history of the development of permanent magnet materials. In 1972 the second generation of Sm2CO17; rare earth permanent magnet material was successfully developed, high performance in 1983. The birth of low-cost third-generation rare-earth permanent magnet material NdFeB laid the dominance of rare earth permanent magnet materials in permanent magnetic materials. In 1993, the output value of rare earth permanent magnets in Japan exceeded the number of permanent magnet ferrites for the first time. It is expected that the global output value of sintered NdFeB in 2000 will reach US$3 billion and exceed that of permanent magnet ferrites. The output of sintered NdFeB will reach $3 billion and exceeds the number of permanent magnet ferrites. The magnetic ability of sintered NdFeB is 12 times that of permanent magnet ferrite. Therefore, in a similar situation, the volume and weight will be greatly reduced, so that high-efficiency and low-energy can be achieved. Nano-composite Sapphire rare-earth permanent magnet material is suitable for the preparation of miniature and special-shaped motors, and is an important direction in the research and application of rare earth permanent magnet materials. The development of soft magnetic materials has gone through the history of crystalline, amorphous, and nanocrystalline states. Nanocrystalline metal soft magnetic material has very excellent performance, high magnetic permeability, low loss, high saturation magnetization, has been applied to switching power supply, transformer. Sensors, etc., can realize device miniaturization, light weight, high frequency, and multi-functionality, and have developed rapidly in recent years. Magnetoelectronic nanostructured devices are the most influential major achievements of the late 20th century. In addition to the giant magnetoresistance effect of read heads, MRAMs, and magnetic sensors, new metal devices such as all-metal transistors are gaining ground. Magnetic electronics has become a popular new discipline.

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