Preparation And Optimization Of Spin Valve Materials Based On SAF Structure

Since the discovery of the Giant Magneto Resistance(GMR)effect in magnetic /non-magnetic multilayer film materials in 1988,giant magnetoresistive materials have rapidly gained industrialization and commercial applications in sensors,storage devices and other fields.Its academic research value and broad market application prospects have attracted wide attention and investment from relevant scientific researchers in universities,research institutes and high-tech companies.In 1991,B.Dieny proposed a four-layer thin film spin valve material structure with a magnetic layer,a non-magnetic isolation layer,a magnetic layer,and an antiferromagnetic layer.Compared with magnetic / non-magnetic multilayer film materials discovered in 1988,spin valve materials has broad application prospects in automotive electronics,industrial control,consumer electronics,and biomedicine due to its advantages such as high sensitivity,sensitivity to magnetic field directions,and low saturation fields.The main work of this thesis is to carry out the preparation,optimization of spin valve materials,and the design and preparation of spin valve sensors.The main thesis of this paper includes: structural design,material selection and process optimization of spin valve materials to obtain high-performance spin valve materials;exploring the growth of spin valve materials on flexible substrates,and laying the foundation for the development of flexible sensors;The design and manufacturing process of sensors for spin valve materials are studied to lay the foundation for the next step in sensor preparation and performance research.This thesis first introduces the research background and application prospects of the GMR effect.Based on the application prospects of spin valve materials in the field of sensors,the purpose and significance of this thesis are put forward.Next,the physical mechanism of the GMR effect and the basic working mechanism of the spin valve material are analyzed.In the structural design,material selection and process optimization of the spin valve material,in order to enhance the magnetic field stability of the material in the device application,an artificial antiferromagnetic material was selected as the pinned layer,and the high vacuum magnetron sputtering method was used in A SAF structure top-pinned spin valve material with a structure of "substrate Ta / Ni Fe /Co Fe / Cu / Co Fe / Ru / Co Fe / Ir Mn / Ta" was prepared on a silicon substrate.Through the optimization of the free layer,Cu layer,pinned layer and pinned layer,especially the key optimization of SAF sandwich structure Co Fe / Ru / Co Fe,the giant magnetoresistance ratio of the spin valve material obtained is 6.4% The exchange bias field is 950 Oe.When optimizing theSAF sandwich structure Co Fe / Ru / Co Fe,by adjusting the relative thickness of the two Co Fe layers,spin valve materials with different properties of positive giant magnetoresistance effect and negative giant magnetoresistance effect were obtained.This provides a new research idea for the design of spin valve sensors.Based on the process optimization results of a silicon-based substrate spin valve material,a flexible polyethylene terephthalata(PET)substrate was used to grow a spin valve material with SAF structure.The material has a giant magnetoresistance ratio of 5% and an exchange bias field of 500 Oe.Compared to a silicon-based substrate,the material’s exchange field is reduced.This is related to the flatness of the substrate surface and the growth interface state of the spin valve material.To improve material properties,further optimization is needed.Further,the structure design and manufacturing process of the sensor based on the spin valve material are studied in this paper.A positive giant magnetoresistance effect material and a negative giant magnetoresistance effect material are proposed to design the sensor,and an in-situ magnetic field modulation structure is set on the core In order to reduce the noise of the sensor,the manufacturing process of the spin valve sensor was designed,which laid the foundation for the next step in the preparation and performance analysis of the spin valve sensor.