摘要
制备了Ta/FePt/C系列多层膜,研究了样品在不同温度退火后的磁特性和微结构.实验结果表明,不同厚度的Ta缓冲层具有不同的微结构特征,显著影响FePt层的L10有序相的形成及相应的矫顽力.当Ta缓冲层较薄,Ta层为非晶态,且较为粗糙,由此使FePt在界面处产生较多的缺陷并导致较高密度的晶界,在退火过程中,受束缚相对较弱的非晶态的Ta原子比较容易沿FePt的缺陷和晶界处向FePt层扩散,使FePt在相变过程中产生的应力比较容易释放,同时,Ta在扩散过程中产生的缺陷,降低了FePt有序化的转变势垒,在较低温度下便形成有序相,因而在合适的Ta层厚度下(1—2nm),样品的矫顽力较之无Ta缓冲层的情形可增强数倍甚至一个数量级.随着Ta缓冲层厚度的增加,其粗糙度减小,随后晶态结构亦开始形成,Ta原子大多被自身晶格束缚,于是Ta缓冲层对FePt的有序相转变以及矫顽力的影响显著减小直至基本消失.
The magnetic and microstructural properties of Ta/FePt/C thin films after annealing at various temperatures have been investigated. The results indicate that for a very thin Ta buffer with amorphous structure and relatively large roughness, defects and grain boundaries of high density are formed in the FePt film grown on it, which effectively lowers the energy barrier of the ordering with Ta interdiffusion into the grain boundaries of the FePt film during the annealing process. The formation of the L10 phase of FePt thin films is thus greatly promoted with the ordering temperature of FePt significantly reduced by introducing a thin Ta buffer layer. On the other hand, when Ta layer is relatively thick, its roughness accordingly reduces, and most of the interfacial Ta atoms are finally bounded with the advent of the crystalline structure of the Ta buffer. Therefore, Ta buffer layer at this thickness range has little effect on the ordering of FePt films.
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2006年第1期450-455,共6页
Acta Physica Sinica
基金
国家自然科学基金(批准号:50271081)资助的课题~~
