磁性隧道结Fe/MgO/Fe(001)的磁性及界面电子结构

MAGNETIC PROPERTIES AND INTERFACE ELECTRONIC STRUCTURE OF THE Fe/MgO/Fe(001)MAGNETIC TUNNELING JUNCTIONS

采用分子束外延技术在GaAs(001)-4×6衬底上外延出Fe/MgO/Fe(001)单晶磁性隧道结.原位表面磁光Kerr效应(SMOKE)测量表明:当外磁场沿[1(?)0]方向时,隧道结的SMOKE回线具有典型的双矫顽力特性.下电极Fe层的矫顽力(约为20mT)约是上电极Fe层矫顽力(约为1mT)的20倍.矫顽力的增强主要被归结为MgO/Fe(001)界面对下电极铁磁层的钉扎作用.自旋分辨的光电子能谱测量表明:在MgO覆盖到Fe(001)表面后,Fe(001)Fermi面的自旋极化率P由负值转变为正值.P值符号的改变被归结为MgO/Fe(001)界面电子自旋结构的改变.

Fully epitaxial Fe/MgO/Fe（001） magnetic tunneling junctions （MTJs） were fabricated on GaAs（001）-4×6 surface. In situ surface magneto-optical Kerr effect （SMOKE） measurements showed thes MOKE loop is of a typical two-step character as the applied magnetic field is along [110] direction. It was found that the coercivity of bottom Fe electrode is about 20 mT which is about 20 times higher than that of top Fe layer. The remarkable increase of the coercivity in the bottom Fe layer is attributed to the pinning effect at MgO/Fe/GaAs （001） interfaces. Spin-resolved valence band photoemission spectroscopy measurements showed that after covering MgO on Fe（001） surface the spin polarization at Fermi level of bcc Fe（001） reversed the sign from negative into positive, which is ascribed to a selective modification of the electronic states involved at the MgO/Fe（001） interface.