Si-Al_2O_3复合薄膜的室温铁磁性

Room-temperature ferromagnetism observed in Si-Al_2O_3 composite film

在Si-Al2O3复合薄膜中观察到室温铁磁性.Si的体积百分比为15%的Si-Al2O3复合薄膜的磁性最强.Si的含量影响样品的磁有序,在样品中观察到了明显的磁畴.在不同气氛下,对样品进行快速热退火.退火样品的磁性测试结果的差别表明氧空位不是样品铁磁性的主要来源.我们认为铁磁性来源于Si与Al2O3基质界面之间的缺陷的磁耦合.改变Si的含量可以改变缺陷密度,从而控制铁磁耦合强度.

Room-temperature ferromagnetism （FM） is observed in Si-Al2O3 amorphous composite film.The magnetic moment is the highest in the case of the Si-Al2O3 composite films with the Si content being 15 vol.%,and distinct domains are detected in our films.The difference in magnetism property between sample annealed in Ar atmosphere and untreated composite film indicates that the observed ferromagnetism does not originate primarily from oxygen defects.It is concluded that the ferromagnetism arises from the direct coupling between defects.These defects orignate from the interface between Si particles and Al2O3 matrix.By varying the Si content in the film,one can change the defect density and thereby control the strength of the ferromagnetic coupling.