Highly spin-polarized current in Co-substituted Fe3O4 epitaxial thin films at room temperature
Highly spin-polarized current in Co-substituted Fe3O4 epitaxial thin films at room temperature
复制标题
DOI：
10.1063/1.4903215
复制
发表时间：
2014-12
影响因子：
3.2
通讯作者：
M. Takahashi;Toshiyuki Ohshima;H. Yamahara;M. Seki;H. Tabata
中科院分区：
文献类型：
--
作者：
M. Takahashi;Toshiyuki Ohshima;H. Yamahara;M. Seki;H. Tabata
采用脉冲激光沉积法在α-Al 2 O3（001）衬底上制备了CoxFe 3 − xO 4（x = 0.0，0.5和1.0）外延薄膜。结果表明，通过改变钴含量可以调节钴铁氧体薄膜的矫顽力。在低氧压（1.0 × 10−6 Pa）下制备的薄膜甚至在x = 1.0时也表现出半导体行为。X-射线光电子能谱显示，所有组合物的Co离子为2+。另一方面，发现Fe离子处于Fe 2 +/Fe 3+价态，这可能导致薄膜中Fe-3d电子之间的小极化子跳跃。一个异常的霍尔效应，观察到在Co0.5Fe2.5O4薄膜，即使在300 K，表明在薄膜中的载流子在室温下是高度自旋极化。
Epitaxial thin films of cobalt ferrite CoxFe3−xO4 (x = 0.0, 0.5, and 1.0) were fabricated on α-Al2O3 (001) substrates using pulsed laser deposition. It was found that the coercive force of the cobalt ferrite films could be tuned by changing the Co content. The films prepared under low oxygen pressure (1.0 × 10−6 Pa) showed semiconducting behavior even for x = 1.0. X-ray photoelectron spectroscopy revealed that the Co ions were 2+ for all compositions. On the other hand, it was found that the Fe ions were in the Fe2+/Fe3+ valence state, which may cause small-polaron hopping among the Fe-3d electrons in the films. An anomalous Hall effect was observed in the Co0.5Fe2.5O4 film even at 300 K, suggesting that carriers in the films were highly spin-polarized at room temperature.