Valenzuela S O, Monsma D J, Marcus C M, Narayanamurti V, Tinkham M
Gordon McKay Laboratory, Harvard University, Cambridge, Massachusetts 02138, USA.
Phys Rev Lett. 2005 May 20;94(19):196601. doi: 10.1103/PhysRevLett.94.196601. Epub 2005 May 16.
A mesoscopic spin valve is used to determine the dynamic spin polarization of electrons tunneling out of and into ferromagnetic (FM) transition metals at finite voltages. The dynamic polarization of electrons tunneling out of the FM slowly decreases with increasing bias but drops faster and even inverts with voltage when electrons tunnel into it. A free-electron model shows that in the former case electrons originate near the Fermi level of the FM with large polarization whereas in the latter, electrons tunnel into hot electron states for which the polarization is significantly reduced. The change in sign is ascribed to the matching of the electron wave function inside and outside the tunnel barrier.
一个介观自旋阀被用于确定在有限电压下进出铁磁（FM）过渡金属的隧穿电子的动态自旋极化。从FM隧穿出来的电子的动态极化随着偏压增加而缓慢降低，但当电子隧穿进入FM时，极化下降得更快，甚至随电压反转。一个自由电子模型表明，在前一种情况下，电子起源于FM费米能级附近，具有大的极化，而在后一种情况下，电子隧穿进入极化显著降低的热电子态。符号的变化归因于隧道势垒内外电子波函数的匹配。
