摘要
PbPd1-xCoxO2透過理論計算具有特殊的能帶結構¬¬，稱為自旋無能隙半導體。由於可能兼具高自旋極化率與大自旋弛豫長度，所以近年來受到相當程度的注目。
本論文經由溶膠凝膠法與旋轉塗佈法製備PbPd0.81Co0.19O2薄膜。薄膜的最優化熱處理工藝被確定為430℃氧化5min+700℃煅燒30min。煅燒之後的薄膜為單相多晶奈米顆粒膜，具有體心正交結構。電性方面，PbPd0.81Co0.19O2薄膜的金屬-絕緣體轉變溫度為358K，遠高於目前報導的其它的PbPd1-xCoxO2材料。薄膜的電導率為溫度的冪指數函數，說明薄膜具有零能隙能帶結構。磁性方面，薄膜具有鐵磁性與超順磁性的共存。鐵磁性為內稟鐵磁性，且保持至380K以上；超順磁性則來源於薄膜內部的大量鐵磁性奈米顆粒。另外，薄膜的還具有兩個有趣的特性：一是飽和磁化量隨溫度上升而增加；二是350K以下飽和磁化量在某個強磁場下會有突降。薄膜特殊的自旋零能隙能帶結構可以用來合理解釋這些特性。

According to the theoretical calculation, PbPd1-xCoxO2, the so-called spin gapless semiconductor, has a special energy band structure. Due to the potential of possessing the high spin polarization and long spin relaxation length, it attracts much attention in recent years.
In this thesis, sol-gel spin coating method was used to fabricate PbPd0.81Co0.19O2 thin film. The optimal parameters of heat treatment were oxidation at 430℃ for 5 min plus calcination at 700 for 30 min. The calcined film was the single-phase multicrystalline nanograin one with a body-center orthorhombic structure. The metal-insulator transition temperature for the PbPd0.81Co0.19O2 film was 358K, much higher than all the PbPd1-xCoxO2 materials reported previously. The film’s conductivity was found to have a power dependence on the temperature, which indicated the film has a gapless energy band structure. As to the magnetic properties, the ferromagnetism and the superparamagnetism coexisted within the film. The ferromagnetism was proved to be intrinsic and persisted up to 380 K. The superparamagnetism was caused by large number of ferromagnetic nanograins. Besides, two interesting features were also observed: one is the saturation magnetization increasing with the temperature; the other is the saturation magnetization measured at <350 K decreasing abruptly at some critical field. The special spin gapless energy band structure of the film were used to explain these phenomena reasonably.

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