Giant Magnetoresistance-Like Effect Observed in a Ferromagnet / Antiferromagnet Bilayer Open Access

Yuan, Weigen (2015)

Permanent URL: https://etd.library.emory.edu/concern/etds/000000549?locale=en
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Abstract

In our research, we mainly studied the electrical resistance (R) of the ferromagnet / antiferromagnet bilayer film under a changing magnetic field (H), and its dependence on bilayer structures and temperature. By fitting our obtained R v.s. H data with two different functions, we found consistently an asymmetry of the asymptotes at the two extreme positive and negative values of H, when temperature is below 250 K. Although anisotropic magnetoresistance (AMR) was the predominant effect captured by our data, it could not be used to explain this observed asymptotical difference. Instead, an entirely new GMR-like model was proposed to accommodate our experimental data. In addition, we also calculated the effective exchange bias field, Hb, of the F/AF bilayer using two different methods: one is through the fitting function parameter, and the other through original data. When we compared the two calculation results of Hb, we found that they were not in perfect agreement. However, our argument for the GMR-like model should not be compromised by this disagreement of calculated Hb.

Table of Contents

1 Introduction

1.1General Concepts in Electromagnetism

1.2 Two Types of Magnetism

1.3Hysteresis Loop and Exchange Bias

1.4 Giant Magnetoresistance

1.5Anisotropic Magnetoresistance

2 Equipment and Procedures

3 Analysis Methods

4 Results

5 Discussion

6 Conclusion

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