Magnesium doping effects on magnetic and electrical transport in MgO based magnetic tunnel junctions
| Autor: | Wen-Hsien Chen, 陳文賢 |
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| Rok vydání: | 2007 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 95 In this thesis, we have systematically investigated the electrical- and magneto-transport properties in MgO-based magnetic tunnel junctions (MTJs), due to Mg doping at the bottom interface, by complex- capacitance (CC) and –impedance (CI) technique. We focus on the sample with/without inserting 4Å Mg discontinuous layer between the bottom CoFe electrode layer and the MgO barrier layer. The tunnel magnetoresistance (TMR) of MTJs with Mg doping shows a apparent increase to ~4%, compared to only 0.76% TMR ratio of MTJs without Mg doping. The corresponding CI and CC spectra with/without Mg doping MTJs are also measured and analyzed by the equivalent circuit model. The analysis indicates inserting 4Å Mg discontinuous layer between the bottom CoFe layer and the MgO barrier layer not only can improve barrier quality, but also decrease interfacial defects. Furthermore, we also use the X-ray reflectivity and high-resolution transmission electron microscopy to confirm the improvement of barrier texture and interfacial conditions. Therefore, we conclude the enhancement of TMR ratio due to 4 Å Mg doping could be related to the improvement of the bottom interfacial smoothness as well as the increase of textured MgO. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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