Begum Husne Ara, Naganuma Hiroshi, Oogane Mikihiko, Ando Yasuo
Department of Applied Physics, Graduate School of Engineering, Tohoku University, 6-6-05, Aza-aoba, Aoba-ku, Sendai 980-8579, Japan.
Materials (Basel). 2011 Jun 9;4(6):1087-1095. doi: 10.3390/ma4061087.
The 10 at.% Co-substituted BiFeO₃ films (of thickness 50 nm) were successfully prepared by radio frequency (r.f.) magnetron sputtering on SrTiO₃ (100) substrates with epitaxial relationships of 001Co-BiFeO₃//001SrTiO₃. In this study, a single phase Co-substituted BiFeO₃ epitaxial film was fabricated by r.f. magnetron sputtering. Sputtering conditions such as Ar, O₂ gas pressure, annealing temperature, annealing atmosphere, and sputtering power were systematically changed. It was observed that a low Ar gas pressure and low sputtering power is necessary to suppress the formation of the secondary phases of BiO. The Co-substituted BiFeO₃ films were crystalized with post-annealing at 600 °C in air. The process window for single phase films is narrower than that for pure BiFeO₃ epitaxial films. By substituting Fe with Co in BiFeO₃, the magnetization at room temperature increased to 20 emu/cm³. This result suggests that Co-substituted BiFeO₃ films can be used in spin-filter devices.
通过射频磁控溅射在具有001Co - BiFeO₃//001SrTiO₃外延关系的SrTiO₃(100)衬底上成功制备了厚度为50 nm的10 at.% Co取代的BiFeO₃薄膜。在本研究中，通过射频磁控溅射制备了单相Co取代的BiFeO₃外延薄膜。系统地改变了诸如Ar、O₂气体压力、退火温度、退火气氛和溅射功率等溅射条件。观察到低Ar气体压力和低溅射功率对于抑制BiO第二相的形成是必要的。Co取代的BiFeO₃薄膜在空气中600℃进行后退火结晶。单相薄膜的工艺窗口比纯BiFeO₃外延薄膜的窄。通过在BiFeO₃中用Co取代Fe，室温下的磁化强度增加到20 emu/cm³。该结果表明Co取代的BiFeO₃薄膜可用于自旋过滤器件。
