结构相变对Fe掺杂TiO_2薄膜室温铁磁性的影响

Influence of structural phase transition on Ferromagnetism in Fe-doped TiO_2 thin films

采用直流磁控溅射方法在玻璃基底上制备了不同Fe掺杂浓度的TiO_2薄膜,并对其晶体结构和磁特性进行了研究.在所有掺杂样品中,均观察到了室温铁磁性,磁性源于Fe离子与其近邻空间分布的空穴相互作用.在掺杂量为7%的锐钛矿相薄膜中观察到了最大的磁化强度.随着Fe掺杂浓度的进一步增加,TiO_2的晶体结构逐渐由锐钛矿相向金红石相转变,并且磁性减弱.不同结构的TiO_2中Ti-O键长不同,导致替代的磁性Fe离子与空穴的作用强度发生改变,进而使其磁性发生变化.

Fe doped TiO_2 films are deposited on glass substrates using dc magnetron sputtering.The crystal structures and the magnetic properties of these films are studied.Room temperature ferromagnetism is observed in each of all the Fe doped TiO_2 films.The source of magnetism is related to an exchange interaction between the transition-metal（Fe） ions and localized strapped holes.The maximal magnetization is observed in a TiO_2 film with Fe concentration 7%.With the increase of Fe concentration,the crystal structure of TiO_2 film transforms gradually from anatase phase to rutile phases,and magnetism in the film weakened.The changes of crystal structure and crystallization in TiO_2 film resulting from Fe doping affect the change of ferromagnetism in the film.