| Summary: | 碩士 === 國立中興大學 === 材料科學與工程學系所 === 101 === The experiment was divided into two parts, (i)Ni80Fe20/Mn and (ii)Ni80Fe20/Cr were prepared by dual ion-beam deposition technique. The structure and magnetic properties were investigated by X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Vibrating Sample Magnetometry (VSM), and also Atomic Force Microscopy (AFM).
(i) The structure is face-centered cubic NiFe (a~3.81 A) phase and body-centered cubic α-Mn (a~8.91 A) phase. Grain sizes ranged from 7 to 16 nm. Under 50 K without the ion beam bombardment of [Ni80Fe20/Mn]50 coercivity (HC) 165 Oe, and with ion beam bombardment coercivity (HC) increased to 265 Oe, and exchange bias (HEX) showing a contrary trend, from -20 Oe to -3 Oe. Field cooled and zero field cooled shows via ion beam bombardment will change its blocking temperature (TB). Magnetoresistance measurements after ion beam bombardment that will decreased. The interplay between interlayer coupling and exchange bias coupling in [NiFe/Mn] multilayer-based thin films was investigated by controlling the configurations from superlattice to nanocomposite or hybrid structured thin films using ion-beam bombardment during deposition. Results have shown that well-defined interfaces in the superlattice [NiFe/Mn] thin film exhibited interlayer coupling behavior. In contrast, an enhanced coercivity was observed in the nanocomposite [NiFe-Mn] thin film. However, the hybrid [NiFe-Mn]/[NiFe/Mn] thin film with an intermixed NiFeMn alloyed film component gave rise to unusual positive exchange bias coupling.
(ii) The structure of body-centered cubic Cr (a~2.90 A) phase. Grain sizes ranged about 10 nm. Magnetometry results [NiFe-Cr] thin film is enhanced by ion-beam bombardment. Under 10 K without the ion bea bombardment of [Ni80Fe20/Cr]50 coercivity (HC) 7 Oe, and with ion beam bombardment coercivity (HC) increased to 250 Oe, and exchange bias (HEX) showing incresae from 2 Oe to 15 Oe. Especially, the Cuire temperature of [NiFe/Cr] was changed by ion-beam bombardment, the range from 160 K to 298 K.
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