11:00 AM, March 3, 2011
Sumwalt, Room 102

Science vol. 331, p. 894 (February 2011)

Spin Selectivity in Electron Transmission Through Self-Assembled Monolayers of Double-Stranded DNA

B. Göhler, V. Hamelbeck, T. Z. Markus, M. Kettner, G. F. Hanne, Z. Vager, R. Naaman, H. Zacharias

In electron-transfer processes, spin effects normally are seen either
in magnetic materials or in systems containing heavy atoms that
facilitate spin-orbit coupling. We report spin-selective transmission
of electrons through self-assembled monolayers of double-stranded DNA
on gold. By directly measuring the spin of the transmitted electrons
with a Mott polarimeter, we found spin polarizations exceeding 60% at
room temperature. The spin-polarized photoelectrons were observed even
when the photoelectrons were generated with unpolarized light. The
observed spin selectivity at room temperature was extremely high as
compared with other known spin filters. The spin filtration efficiency
depended on the length of the DNA in the monolayer and its
organization.