Development of high quality ferromagnetic tunnel barrier and realization of tunneling spin filter devices

本文研究了具有垂直磁各向异性的CoFe_2O_4铁磁绝缘子的隧穿-自旋滤波效应。为了提高CoFe_2O_4薄膜的表面平整度，采用脉冲激光沉积法在MgO（001）衬底上生长CoFe_2O_4薄膜。得到了垂直各向异性能量密度为2.36 × 106 erg/cm3的无液滴CoFe_2O_4薄膜。采用MgO/CoFe_2O_4和在MgO（001）衬底上制备的铁磁性金属l10型FePd电极对磁隧道结（MTJs）进行了磁阻测量。在5k和300k下，MTJs的隧道磁阻比分别为0.7%和16.5%。

In this study, tunneling-spin filtering effect of ferromagnetic insulator CoFe_2O_4 with perpendicular magnetic anisotropy was studied. To improvement surface flatness of CoFe_2O_4 films, the films were grown on MgO(001) substrates by pulse laser deposition method with a shadow mask. The CoFe_2O_4 films without droplet formation with perpendicular anisotropy energy density of 2.36x106 erg/cm3 were obtained. Magnetoresistance measurements were carried out for magnetic tunnel junctions (MTJs) using MgO/CoFe_2O_4 and ferromagnetic metal L10-type FePd electrodes fabricated on MgO (001) substrates. The tunnel magnetoresistance ratio of 0.7% at 5 K and 16.5% at 300 K was obtained for the MTJs.