Fe3O4/MgO超晶格的低維結構與電性

• Main Author: 劉昊明
• Other Authors: 陳恭
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/19397332767261986851

碩士 === 國立中正大學 === 物理系 === 91 === Fe3O4 has not only almost 100% spin-polarization but also highly Curie temperature Tc=858K. The combination of these properties makes Fe3O4 become the ideal magneto-resistance material and attracts our interest in studying. Single crystalline Fe3O4/MgO superlattices have been grown on MgO(001) substrate by using oxygen-plasma-assisted molecular beam epitaxy. Superlattices consisting of fixed thickness of MgO layer 20Å and varied thickness of Fe3O4 layer of 10~320Å have been synthesized with 30-45 bilayer repeats. This system provides an opportunity to study the low dimensional effect of the structure and physical properties of Fe3O4. After the samples being epitaxed, we measured the structures of these samples with x-ray diffraction and calculated their modulation wavelength by satellite peaks. Then, in the additional magnetic filed H=0 or H=1T, we measured the resistance difference of these samples between T=100~300K. We found out that the resistivity of these films increased with decreasing film thickness. The cause of this phenomenon is the result that Fe3O4 mismatches with the substrate during the process of being epitaxed. There are also many related reports about this phenomenon.