Park B G, Banerjee T, Lodder J C, Jansen R
MESA+ Institute for Nanotechnology, University of Twente, 7500 AE Enschede, The Netherlands.
Phys Rev Lett. 2007 Nov 23;99(21):217206. doi: 10.1103/PhysRevLett.99.217206. Epub 2007 Nov 20.
The variation of the tunnel spin-polarization (TSP) with energy is determined using a magnetic tunnel transistor, allowing quantification of the energy dependent TSP separately for both ferromagnet/insulator interfaces and direct correlation with the tunnel magnetoresistance (TMR) measured in the same device. The intrinsic TSP is reduced below the Fermi level, and more strongly so for tunneling into empty states above the Fermi level. For artificially doped barriers, the low bias TMR decreases due to defect-assisted tunneling. Yet, this mechanism becomes ineffective at large bias, where instead inelastic spin scattering causes a strong TMR decay.
利用磁隧道晶体管确定隧道自旋极化（TSP）随能量的变化，从而能够分别对铁磁体/绝缘体界面的能量相关TSP进行量化，并与在同一器件中测量的隧道磁电阻（TMR）直接关联。本征TSP在费米能级以下降低，对于隧穿到费米能级以上的空态而言，降低得更为显著。对于人工掺杂的势垒，低偏置下的TMR由于缺陷辅助隧穿而降低。然而，这种机制在大偏置时变得无效，此时非弹性自旋散射导致TMR强烈衰减。
