Grow YIG Magnetic Film By PLD And 3D Magnetic Absorbing Structure

This paper is divided into two parts:YIG magnetic thin films prepared by pulsed laser deposition and 3D absorbing structures designed and fabricated.Since the discovery of giant magnetoresistance effect in 1988,various spin-related physics,materials and devices have attracted much attention and carried out extensive research.non-volatile memory based on magnetic tunneling and spin valve devices based on spintronics have gone from factory to market.In spintronics,the transmission of spin signal does not depend on the movement of charges,which avoiding the generation of joule heat.In order to study and improve the transport characteristics of spin current signals,it is necessary to prepare good spin transport materials.This paper synthesizes the experimental results of the existing literature.This paper explored the process parameters of yttrium iron garnet(YIG)grown by pulsed laser deposition(PLD).We used Si<100>and GGG<111>as substrates and optimized growth process parameters,such as growth temperature,growth pressure and laser frequency,to manufacture monocrystalline YIG films.After optimization,high quality YIG samples were prepared under the conditions of oxygen pressure 7.5 mTorr and laser repetition rate 4 Hz.The surface roughness was less than 1 nm and the growth rate was 2 nm/min.Absorbing material is an important application material in the research of radio frequency,millimeter wave,terahertz and other frequency bands.In order to improve the absorption efficiency and reduce the thickness of the absorbing coating,two kinds of artificial electromagnetic structures with three-dimensional structure were designed,and the samples were prepared by using three-dimensional printing technology,and the reflectivity was measured and the results were analyzed.The two structures are:the quadripyramidal cavity periodic structure with the cone tip outward,the quadripyramidal cavity periodic structure with the square bottom and the quadripyramidal cavity periodic structure with the cone tip inward.Firstly,the electromagnetic simulation software HFSS is used to simulate the models with different sizes fixed to 12 mm3.The results show that when the bottom edge is 1 mm and the height is 12 mm,the absorption bandwidth is large and the absorption rate is high.When the bottom edge is 2 mm and the height is 3 mm,the absorption bandwidth is 8 GHz.Considering that the thickness of absorbing layer should not exceed 3 mm in practical use,we made 2 mm*2 mm*3 mm samples and measured their reflectivity.The results show that they have obvious absorbing effects at 2-5 GHz and 10-18 GHz.