| Summary: | 碩士 === 國立中興大學 === 材料科學與工程學系所 === 106 === In this study, the Ag(1min)/MnBi(5,10,20,30min)/SiO2/Si, Ta(1min)/MnBi (5min)/Bi(5min)/SiO2/Si and Ta、SiO2(1min)/MnBi(20min)/Bi(5min)/Si thin film were prepared using a dual ion beam sputtering deposition technique. Ag, Ta, and SiO2 as a capping layer to prevent Mn oxidation and Bi diffusion. Then use magnetic field annealing (MFA, Happ. = 5000 Oe perpendicular to the film at 400°C for 1 hour under vacuum) and a rapid thermal annealing (RTA, at 350°C for 1 hour under Ar gas) to investigated the effects of different sputtering time and with different capping layers and use different annealing modes.
Results of XRD showed that the as-deposited film has a weak peak, the longer sputtering time of the MnBi layer has more crystal phases, the MnBi exhibited a H.C.P. structure (lattice constant a~4.268 Å, c~6.115 Å); After annealing, the MnBi has strong peak and good crystallinity, but preferred orientation change and the structural phase transformation from H.C.P. to Orthorhombic. TEM cross-section image shows that after annealing Ag diffused into MnBi; SiO2 sputtering time is too short to from the film, Mn oxidation and Bi evaporation, and some areas become amorphous. The result of magnetic properties have shown that the coercivity (Hc) of Ag(1m)/MnBi(10m) from the AGM is about 89 Oe due to the annealing process has a vertical magnetic field (5000 Oe) to make it a weak hysteresis curve. No ferromagnetism signal in Ta、SiO2/MnBi /Bi/Si samples, because no LTP-MnBi was formed.
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