Spin polarization with a twist Nancy P. Sandler, Ohio University, DMR MWN/CIAM COLLABORATION USA-Brazil-Chile A well-known relativistic effect, the spin-orbit interaction, couples the spin of the electron to its dynamics. In a carbon nanotube, the curvature enhances this effect and results in sizeable responses. Interestingly, an externally applied electric field without parity inversion symmetry results in a transmission function which exhibits preference for one direction of the spin whenever a current is passed through this active region. current leadactive regioncurrent lead Puller et al. EPL 77, (2007) An example of such field is the one arising from a wrapped DNA molecule on the nanotube (used to aid the selectivity in its separation after synthesis—see fig. on left). The effect (fig. on right) is stronger for longer DNA wrappings.

What does Rashba do to Kondo? Nancy P. Sandler, Ohio University, DMR MWN/CIAM COLLABORATION USA-Brazil-Chile Zarea et al, arXiv: The spin-orbit interaction (SOI), which couples the spin of the electron to its dynamics, has been repeatedly blamed and exonerated over the years from having deleterious effects on the Kondo screening. The latter can be described as giving rise to a spin singlet cloud surrounding a magnetic impurity embedded in a metal. As such, the dynamical twist imparted by the SOI would be expected to play an important role on the strength and features of the Kondo effect. In a two-dimensional system with strong Rashba SOI, we have demonstrated that the Kondo screening of a magnetic impurity develops in fact an interesting twist: a rotational term of the form known as a Dzyaloshinsky-Moriya interaction. This term results in a strong enhancement of the Kondo temperature for the most general case of no particle-hole symmetry and it should manifest in graphene (with its additional Dirac points) and other two-dimensional systems. Graphene exhibits additional Dirac points due to Rashba SOI – Zarea and Sandler, Phys. Rev. B (2009) – and ~20% Kondo temperature enhancement due to SOI Rashba SOI strength

Busy APS March Meeting & DC Congressional Visit Nancy P. Sandler, Ohio University, DMR MWN/CIAM COLLABORATION USA-Brazil-Chile The Ohio University groups of Sandler and Ulloa at the 2011 APS March Meeting included 7 graduate students and 1 postdoc, in addition to the co- PI’s. A total of 12 papers were presented at the conference. The group included an exchange student, Diego Mastrogiussepe, part of the CIAM/MWN collaboration. Dieg o Sergio Ulloa participated in the April 2011 Congressional Visits organized by the American Physical Society. These visits with members of both Houses help establish lines of communication with their staff to further understanding about the role of science in the US and especially in their home districts. It also provides the visitors with interesting insights about government functioning.