Research

Spintronics with chiral molecules Sensors – Molecular Controlled Semi-conductor Resistor (MOCSER)  Interaction of electrons with organic and bio-molecules Nanoparticles based hybird systems Chemical Surface Patterning

Spintronics with chiral molecules 

Spin transmission through DNA monolayers

Using the photoelectron spectroscopy methods, we first showed at 1999 that the interaction of electrons with chiral molecules is spin dependent. Recently, in collaboration with the group of Zacharias in Munster, Germany, we found that self-assembled monolayers of DNA are a very efficient spin filters at room temperature. It is known that when ejecting electrons from Au substrate, one can control their spin population with the direction of circular polarized light due to high spin-orbit coupling (see below bottom-left graph). Surprisingly, we found that when a double-strand DNA (dsDNA) was self-assembled on the Au substrate, the ejected electrons were found to have the same spin population even for linear polarized light (see below-the graphs on the right column).

• K. Ray, S. P. Ananthavel, D. H. Waldeck, R. Naaman, Science 1999, 283, 814.

• B. Göhler,V. Hamelbeck, T.Z. Markus, M. Kettner, G.F. Hanne, Z. Vager, R. Naaman, H. Zacharias, Science 2011, 331, 894.

• S.G. Ray, S.S. Daube, G. Leitus, Z. Vager, R. Naaman, Phys. Rev. Lett. 2006, 96, 036101.

 

Spin transport through DNA-nanoparticle assemblies.

This effect of spin filtering by dsDNA was revealed by spin-dependent electron transport measurements as well. We applied conductive-AFM measurement on gold-nanoparticle-dsDNA assemblies on top of nickel substrate as a function of the magnetization direction in the nickel substrate, controlled by the direction of a magnet below the sample (see cartoons below). We found that the assemblies conduct better, when the magnetization is “down” compared to the “up” magnetization. This finding is consistent for several DNA molecules varied by the length (see current-voltage graphs below – blue and red curves stand for magnetization “down” and “up” respectively)  

• Z. Xie, T. Z. Markus, S. R. Cohen, Z. Vager, R. Gutierrez, R. Naaman, Nano Lett. 2011, 11, 4652.

These works opens a new field in which a relation between chirality and spin properties is investigated. Theoretical calculations, performed together with the group of Giovanni Cuniberti and Rafael Gutierrez from Dresden, provided a good understanding of the mechanism. Beyond the contribution to the basic understanding on chirality, its origin, etc. this work also suggests the possibility of applying chiral molecules as spin filters in futuristic spintronics applications. We are currently working towards these devices as well as towards the probing of the role of spin in electron transfer in biological systems.

 

                                                              

• R. Gutierrez, E. Diaz, R. Naaman, G. Cuniberti,  Phys. Rev B, 2012,  in press (rapid communication).

 


 

For more details on specific projects, see the following:

  Sensors – Molecular Controlled Semi-conductor Resistor MOCSER
  Interaction of electrons with organic and bio-molecules
  Charge and energy transfer in hybrid organic-inorganic systems
  Chemical Surface Patterning