Spin polarization

Chirality-Induced Spin Polarization Places Symmetry Constraints on Biomolecular Interactions

  • By Aude Marjolin
  • 1 March 2017

In an article in the Proceedings of the National Academy of Science (doi: 10.1073/pnas.1611467114), David Waldeck and colleagues in Israel propose a mechanism for the enantioselectivity (chiral specificity) of non-covalent interactions between chiral molecules. Their study examines how the non-covalent interactions between molecules give rise to enantioselective interaction energies. Non-covalent interactions do not involve the formation of a bond; rather they include electrostatic interactions between permanent or induced dipoles as the electron clouds of the molecules rearrange and the purely quantum exchange interaction as the wavefunctions of the molecules overlap. Their two part study shows experimentally that charge redistribution in chiral molecules is accompanied by spin polarization and it shows theoretically that the exchange interactions for homochiral (both molecules have the same handedness) interactions differ from heterochiral ones.

Ultrafast Optical Measurements of Spin Polarization in Semiconductors

Vanessa Sih
Monday, September 12, 2016 - 4:30pm

While both spin dynamics and electron orbital motion have been separately studied for many decades, we are just beginning to probe and understand the intricate phenomena that may be expected in the presence of spin-momentum coupling.  For example, it is still a mystery what the microscopic mechanism is that produces a bulk electron spin polarization in semiconductors in response to an applied accelerating electric field and how the electrical spin generation rate depends on material parameters.  Existing theories predict that the magnitude of this electrically-...