Many Co-based Heusler alloys with the stoichometric composition X2YZ are ideal candidates for the spintronics applications. So, they have been extensively studied theoretically and experimentally. The aim of this work was to investigate the effect heat treatment on phase stability and magnetic properties for quaternary Co2FeSi1-xGax Heusler alloys with varying Si concentration. The Co2FeSi1-xGax alloy samples were prepared by conventional arc melting technique. The structure of Co2FeSi1-xGax bulk alloys were examined by powder x-ray diffraction and differential scanning calorimetry. It was confirmed that Co2FeSi1-xGax alloys display the L21 type structure for all x compositions based on the annealing temperature. The magnetic ordering transition temperature, Tc, was measured by differential scanning calorimetry. It was found that the order-disorder phase transition temperature from the L21 to the B2 structure, T , decreases while the Curie temperature, Tc, increases with increasing x / however, the value of these temperatures were not influenced by changing heat treatment process. The magnetic properties of Co2FeSi1-xGax alloy were investigated by using vibrating sample magnetometer. Higher saturation value was obtained at the L21 phase than the value obtained at the B2 phase. It was concluded that the Co2FeSi0.2Ga0.8 alloy was chosen optimum composition for spintronics applications because of its highest Curie temperature and phase stability of L21.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/12613660/index.pdf |
| Date | 01 September 2011 |
| Creators | Kalkanci, Mine |
| Contributors | Akdeniz, Vedat |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | M.S. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for public access |
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