Gao Li, Jiang Xin, Yang See-Hun, Burton J D, Tsymbal Evgeny Y, Parkin Stuart S P
IBM Research Division, Almaden Research Center, San Jose, California 95120, USA.
Phys Rev Lett. 2007 Nov 30;99(22):226602. doi: 10.1103/PhysRevLett.99.226602. Epub 2007 Nov 27.
Tunneling anisotropic magnetoresistance (TAMR) is observed in tunnel junctions with transition metal electrodes as the moments are rotated from in-plane to out-of-plane in sufficiently large magnetic fields that the moments are nearly parallel to one another. A complex angular dependence of the tunneling resistance is found with twofold and fourfold components that vary strongly with bias voltage. Distinctly different TAMR behaviors are obtained for devices formed with highly textured crystalline MgO(001) and amorphous Al2O3 tunnel barriers. A tight-binding model shows that a fourfold angular dependence can be explained by the presence of an interface resonant state that affects the transmission of the contributing tunneling states through a spin-orbit interaction.
在具有过渡金属电极的隧道结中观察到隧穿各向异性磁电阻（TAMR），当磁矩在足够大的磁场中从面内旋转到面外时，磁矩彼此几乎平行。发现隧穿电阻具有复杂的角度依赖性，其双重和四重分量随偏置电压强烈变化。对于由高度织构化的晶体MgO(001)和非晶Al2O3隧道势垒形成的器件，获得了明显不同的TAMR行为。一个紧束缚模型表明，四重角度依赖性可以通过存在一个界面共振态来解释，该共振态通过自旋轨道相互作用影响贡献隧穿态的传输。
