January 31, Sinisa Coh, University of California at Berkeley

coh3:00 PM in Room 205, 8 St. Mary’s Street

Refreshments served at 2:45 PM

Controlling Atomic Movement on the Nanoscale

Abstract: Some of the grand challenges in nanoscience are the ability to control movement of atoms either to propel nanometer-sized machines, or to
synthesize novel electronic devices and materials. To that end, electrical current can be used to move a wide range of metals (Fe, Cu, W, In, Ga) along the outside and inside of a carbon nanotube. In this talk I will present a peculiar mechanism in which these metals move. For example, this mechanism allows an iron nanocrystal to pass through a constriction in the carbon nanotube with a smaller cross-sectional area than the nanocrystal itself. Remarkably, while passing through a constriction, the nanocrystal remains largely solid and crystalline and the carbon nanotube is unaffected. This behavior is accounted for by a pattern of iron atom motion and rearrangement on the surface of the nanocrystal. The nanocrystal motion can be described with a model whose parameters are nearly independent of the nanocrystal length, area, temperature, and electromigration force magnitude. I will also discuss implications of this work on synthesis of nanocomposite materials, and on the stability of carbon-based electronic devices.

More details can be found in these publications:
Phys. Rev. Lett. 110, 185901 (2013)
http://link.aps.org/doi/10.1103/PhysRevLett.110.185901

Phys. Rev. B 88, 045424 (2013)
http://link.aps.org/doi/10.1103/PhysRevB.88.045424

Biography: Sinisa Coh is a postdoctoral fellow in the Department of Physics at the University of California at Berkeley and Lawrence Berkeley National Laboratory. He obtained PhD in physics from Rutgers University in 2011 and BS in physics from the University of Zagreb in 2006. Dr. Coh is a computational materials theorist working on nanostructures, complex oxides, layered materials, topological insulators, and optical properties of materials.

Faculty Host: David Bishop

Student Host: Constantinos Katevatis