Scientists everywhere are trying to study the electrical properties of single molecules. With controlled stretching of such molecules, Cornell researchers have demonstrated that single-molecule devices can serve as powerful new tools for fundamental science experiments. Their work has resulted in detailed tests of long-existing theories on how electrons interact at the nanoscale.
The work, led by professor of physics Dan Ralph, is published in the June 10 online edition of the journal Science. First author is Joshua Parks, a former graduate student in Ralph's lab.
The scientists studied particular cobalt-based molecules with so-called intrinsic spin -- a quantized amount of angular momentum. Theories first postulated in the 1980s predicted that molecular spin would alter the interaction between electrons in the molecule and conduction electrons surrounding it, and that this interaction would determine how easily electrons flow through the molecule.
After releasing the tension, the molecule returned to its original shape and began passing current more easily -- thus showing the molecule had not been harmed. Measurements as a function of temperature, magnetic field and the extent of stretching gave the team new insights into exactly what is the influence of molecular spin on the electron interactions and electron flow.
The effects of high spin on the electrical properties of nanoscale devices were entirely theoretical issues before the Cornell work, Ralph said. By making devices containing individual high-spin molecules and using stretching to control the spin, the Cornell team proved that such devices can serve as a powerful laboratory for addressing these fundamental scientific questions.
The study was funded primarily by the National Science Foundation through the Cornell Center for Materials Research, a Materials Research Science and Engineering Center. ##
Contact: Blaine Friedlander firstname.lastname@example.org 607-254-8093 Cornell University