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Project Details |
Funding Scheme : | General Research Fund | ||||||||||||||||||||||||
Project Number : | 704911 | ||||||||||||||||||||||||
Project Title(English) : | Low-frequency noise study on junction geometry of magnetic tunnel junction (MTJ) sensors for enhancing sensitivity | ||||||||||||||||||||||||
Project Title(Chinese) : | 基於提高磁隧道結傳感器靈敏度及其幾何尺寸對低頻噪聲影響的研究 | ||||||||||||||||||||||||
Principal Investigator(English) : | Dr Pong, Philip Wing Tat | ||||||||||||||||||||||||
Principal Investigator(Chinese) : | |||||||||||||||||||||||||
Department : | Department of Electrical and Electronic Engineering | ||||||||||||||||||||||||
Institution : | The University of Hong Kong | ||||||||||||||||||||||||
E-mail Address : | ppong@eee.hku.hk | ||||||||||||||||||||||||
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Co - Investigator(s) : |
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Panel : | Physical Sciences | ||||||||||||||||||||||||
Subject Area : | Physical Sciences | ||||||||||||||||||||||||
Exercise Year : | 2011 / 12 | ||||||||||||||||||||||||
Fund Approved : | 473,333 | ||||||||||||||||||||||||
Project Status : | Completed | ||||||||||||||||||||||||
Completion Date : | 11-4-2014 | ||||||||||||||||||||||||
Project Objectives : |
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Abstract as per original application (English/Chinese): |
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Realisation of objectives: | 1. All the project objectives have been achieved. 2. As suggested by the RGC Panel Member in the previous progress report, we have now completed the analysis of the experimental results. We have written up and published these experimental results in the journal paper "Comprehensive noise characterization of magnetic tunnel junction sensors for optimizing sensor performance and temperature detection" published in the SCI journal "Materials Research Innovations" and also presented these experimental results in the International Conferences of Asian Union of Magnetics Societies (IcAUMS) 2014. | ||||||||||||||||||||||||
Summary of objectives addressed: |
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Research Outcome | |||||||||||||||||||||||||
Major findings and research outcome: | As suggested by the RGC Panel Member in the previous progress report, all the analysis of the experimental results were completed and published in the journal paper "Comprehensive noise characterization of magnetic tunnel junction sensors for optimizing sensor performance and temperature detection" published in the SCI journal "Materials Research Innovations" and also presented these experimental results in the International Conferences of Asian Union of Magnetics Societies (IcAUMS) 2014. Major research outputs: 5 peer-reviewed journal papers (3 on experimental results, 2 on theoretical calculation results) 6 papers presented in recognized international conferences 3 PhD students trained and graduated Major findings: 1. We have investigated the influence of junction geometry on the noise spectrum of a magnetic tunnel junction (MTJ) sensor. The fluctuation of the MTJ sensor was extracted from the micromagnetic simulation result. A noise analysis program was written in MATLAB to carry out fast fourier transform on the fluctuation to obtain the noise spectrum. The effect of the junction geometry, particularly the edge effect, was found to have significant influence on the noise performance of the sensor. 2. We carried out noise measurement on them to find out its relation between noise and junction area. The measurement experiments have been completed, and we completed the analysis of all the experimental results. Further physical insights on how junction area should be optimized to minimize the sensor noise were obtained. 3. We carried out noise measurement on them to find out its relation between noise and insulating oxide barrier. The measurement experiments have been completed, and we completed the analysis of all the experimental results. Further physical insights on how thickness of insulating oxide barrier should be optimized to minimize the sensor noise were obtained. 4. We carried out noise measurement on them to find out its relation between noise and magnetic free layer. The measurement experiments have been completed, and we completed the analysis of all the experimental results. Further physical insights on how thickness of magnetic free layer should be optimized to minimize the sensor noise were obtained. 5. We have made significant progress on optimizing the junction geometry. We have applied what we have learned from objectives 2, 3, and 4 in fabricating optmized MTJ sensors. | ||||||||||||||||||||||||
Potential for further development of the research and the proposed course of action: |
For the past 20 years, magnetic sensors have found enormous applications in many aspects. Detection of ultralow magnetic fields between 1 femtoTesla to about 100 picoTesla has significant practical applications in weapon detection and biomedical imaging. Magnetoresistive thin film sensors are a very promising candidate for this purpose because they are low-cost, low-power, and portable. Learning from the results of this GRF research project, there are good reasons to believe that this type of sensor technology can be pushed into the 1 picoTesla regime by using magnetic tunnel junctions (MTJs) because MTJs have a large magnetoresistance (MR) and they can be made with low noise. We should move on to work on the ultimate fabrication of the ultrasensitive MTJ magnetic field sensors with 1 picoTesla sensitivity at low frequency. | ||||||||||||||||||||||||
Layman's Summary of Completion Report: | The research outcomes of this project created great impact in pushing forward the frontier of scientific knowledge on low-frequency noise and advancing spintronic magnetic sensor technology on noise reduction. The mechanisms of electronic 1/f noise and magnetic 1/f noise have been revealed. This study sheds light on the unknown 1/f noise mechanism and completes the theoretical model. The research results also provide clear design guidance for reducing sensor noise level and improving sensor sensitivity by fine-tuning the MTJ junction geometry. | ||||||||||||||||||||||||
Research Output | |||||||||||||||||||||||||
Peer-reviewed journal publication(s) arising directly from this research project : (* denotes the corresponding author) |
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Recognized international conference(s) in which paper(s) related to this research project was/were delivered : |
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Other impact (e.g. award of patents or prizes, collaboration with other research institutions, technology transfer, etc.): |
SCREEN ID: SCRRM00542 |