A phenomenological theoretical model for magnetic multilayer based on Boltzmann equation and Fuchs-Sondheimer theory is studied. An oscillatory transmission coefficient (Ts) is introduced into the boundary conditions ...A phenomenological theoretical model for magnetic multilayer based on Boltzmann equation and Fuchs-Sondheimer theory is studied. An oscillatory transmission coefficient (Ts) is introduced into the boundary conditions to simulate the alternate ferromagnetic and anti-ferromagnetic coupling between the magnetic layers. The transmission coefficient has an oscillatory factor relating to the thickness of space layer. Other effects such as interface roughness on Ts are also taken into account. The numerical results for [Fe/Cr]n multilayer agree with the experimental data very well, both in the period and range of osciallation, which is leaded by the dependence of giant magnetoresistance(GMR) on layer thickness of space layer.展开更多
The structure and microfabrication,the detecting theory and the way of biomolecular recognition device based on giant magnetoresistance(GMR) effect are introduced,also the signal detecting and processing instrumentati...The structure and microfabrication,the detecting theory and the way of biomolecular recognition device based on giant magnetoresistance(GMR) effect are introduced,also the signal detecting and processing instrumentation are presented. Here the GMR biosensor was fabricated with magnetic tunnel junction(MJT) material.The biomolecular recognition device contains an array of MJT sensors,single MJT sensor size is 10μm×20μm,tunneling magnetoresistance ratio(TMR) at room temperature is 52.2%,the typical values of junction resistance-area product Rs is 2.6 kΩμm^2,detecting sensitivity of this system is about 8×10^(-4) A·m^(-1).Bioadaptation layer of this device was fabricated with PDMS the thickness of which is less than 100 nm.展开更多
The magnetoresistance behavior and the magnetization reversal mode of NiFe/Cu/CoFe/IrMn spin valve giant magnetoresistance （SV-GMR） in nanoscale were investigated experimentally and theoretically by nanosized magnet...The magnetoresistance behavior and the magnetization reversal mode of NiFe/Cu/CoFe/IrMn spin valve giant magnetoresistance （SV-GMR） in nanoscale were investigated experimentally and theoretically by nanosized magnetic simulation methods. Based on the Landau-Lifshitz-Gilbert equation, a model with a special gridding was proposed to calculate the giant magnetoresistance ratio （MR） and investigate the magnetization reversal mode. The relationship between MR and the external magnetic field was obtained and analyzed. Studies into the variation of the magnetization distribution reveal that the magnetization reversal mode, that is, the jump variation mode for NiFe/Cu/CoFe/IrMn, depends greatly on the antiferromagnetic coupling behavior between the pinned layer and the antiferromagnetic layer. It is also found that the switching field is almost linear with the exchange coefficient.展开更多
为了减少常规涡流检测系统的人工干预程度,便于实现自动化检测,文中采用高灵敏度的巨磁电阻(GMR)芯片作为敏感元件,设计了一款新型的无损探测系统。该系统基于涡流检测的基本原理,采用AD9850直接频率合成器和TDA2030A功率放大芯片搭建...为了减少常规涡流检测系统的人工干预程度,便于实现自动化检测,文中采用高灵敏度的巨磁电阻(GMR)芯片作为敏感元件,设计了一款新型的无损探测系统。该系统基于涡流检测的基本原理,采用AD9850直接频率合成器和TDA2030A功率放大芯片搭建交变电流信号发生电路,利用GMR磁传感器来提取被测金属有缺陷时引起的涡流磁场变化量。文中利用Ansfot Maxwell软件进行了验证,当线圈通以200 m A交变电流时,缺陷处磁场变化量为0.3 m T,通过GMR传感器可以灵敏地探测到该磁场的变化量,因此可以根据传感器输出的电压信号直观地检测到被测金属的缺陷情况。展开更多
文摘A phenomenological theoretical model for magnetic multilayer based on Boltzmann equation and Fuchs-Sondheimer theory is studied. An oscillatory transmission coefficient (Ts) is introduced into the boundary conditions to simulate the alternate ferromagnetic and anti-ferromagnetic coupling between the magnetic layers. The transmission coefficient has an oscillatory factor relating to the thickness of space layer. Other effects such as interface roughness on Ts are also taken into account. The numerical results for [Fe/Cr]n multilayer agree with the experimental data very well, both in the period and range of osciallation, which is leaded by the dependence of giant magnetoresistance(GMR) on layer thickness of space layer.
文摘The structure and microfabrication,the detecting theory and the way of biomolecular recognition device based on giant magnetoresistance(GMR) effect are introduced,also the signal detecting and processing instrumentation are presented. Here the GMR biosensor was fabricated with magnetic tunnel junction(MJT) material.The biomolecular recognition device contains an array of MJT sensors,single MJT sensor size is 10μm×20μm,tunneling magnetoresistance ratio(TMR) at room temperature is 52.2%,the typical values of junction resistance-area product Rs is 2.6 kΩμm^2,detecting sensitivity of this system is about 8×10^(-4) A·m^(-1).Bioadaptation layer of this device was fabricated with PDMS the thickness of which is less than 100 nm.
基金financially supported by the National Natural Science Foundation of China (Nos. 61025021and 60936002)the National Key Project of Scienceand Technology of China (Nos. 2009ZX02023-001-3 and 2011ZX02403-002)the Independent Scientific Research of Tsinghua University (No. 2010THZ0)
文摘The magnetoresistance behavior and the magnetization reversal mode of NiFe/Cu/CoFe/IrMn spin valve giant magnetoresistance （SV-GMR） in nanoscale were investigated experimentally and theoretically by nanosized magnetic simulation methods. Based on the Landau-Lifshitz-Gilbert equation, a model with a special gridding was proposed to calculate the giant magnetoresistance ratio （MR） and investigate the magnetization reversal mode. The relationship between MR and the external magnetic field was obtained and analyzed. Studies into the variation of the magnetization distribution reveal that the magnetization reversal mode, that is, the jump variation mode for NiFe/Cu/CoFe/IrMn, depends greatly on the antiferromagnetic coupling behavior between the pinned layer and the antiferromagnetic layer. It is also found that the switching field is almost linear with the exchange coefficient.
文摘为了减少常规涡流检测系统的人工干预程度,便于实现自动化检测,文中采用高灵敏度的巨磁电阻(GMR)芯片作为敏感元件,设计了一款新型的无损探测系统。该系统基于涡流检测的基本原理,采用AD9850直接频率合成器和TDA2030A功率放大芯片搭建交变电流信号发生电路,利用GMR磁传感器来提取被测金属有缺陷时引起的涡流磁场变化量。文中利用Ansfot Maxwell软件进行了验证,当线圈通以200 m A交变电流时,缺陷处磁场变化量为0.3 m T,通过GMR传感器可以灵敏地探测到该磁场的变化量,因此可以根据传感器输出的电压信号直观地检测到被测金属的缺陷情况。
