Monday, June 5, 2017
2:00 pm
Noyes 153 (J. Holmes Sturdivant Lecture Hall)

Special Chemical Physics Seminar

First-row seats for “the photonic control of single atoms, charges and spins in nanostructures”. Courtesy of femtosecond electron microscopy
Fabrizio Carbone, Assistant Professor, Laboratory for Ultrafast Microscopy and Electron Scattering (LUMES), Institute of Physics, Lausanne Center for Ultrafast Science (LACUS), Ecole Polytechnique Federale de Lausanne (EPFL), Switzerland

Abstract:

         The ability to control individual ions, molecules, charges or spins will allow for the extreme miniaturization of devices, but even more importantly it will revolutionize their energy consumption and range of operation. At the nanoscale, the control parameters available for switching electronic transport, magnetization, or for enabling a specific chemical reaction or structural distortion are typically electromagnetic fields, temperature, local strain, chemical or light-induced doping. So far, either the observation of the dynamics of the individual constituents of an ensemble upon external control, or the control of single objects revealed in ensemble measurements have been achieved.

         We will discuss a roadmap towards the implementation of simultaneous local control and probe experiments targeted at handful amounts of atoms, charges and spins. To achieve this goal, in our laboratory we combined ultrafast electron diffraction, imaging and spectroscopy and applied them to a variety of problems among which we will discuss here three representative examples.

         First, by means of femtosecond electron diffractive imaging, we explored the photomechanical properties of coated gold nanoparticles and demonstrated that local mechanical strength comparable to that of graphene can be attained in self-assembled supracrystals.

By combining imaging and spectroscopy in an ultrafast Transmission Electron Microscope, we demonstrated the ability to control and map electromagnetic fields and charge densities all the way to the nm and attosecond scales, revealing new fundamental phenomena with great potential for the generation and manipulation of confined light.

Lastly, we will show that thanks to such space-specific control abilities we could master the emergence of individual skyrmions in topological magnets, opening intriguing perspectives for high-density and low-energy consumption spin-based read and write storage devices.

         A broader perspective on these kind of experiments, with particular attention to the control and spectroscopy of single molecules and add-atoms on nano-patterned surfaces will be introduced as well.

Contact Priscilla Boon pjboon@caltech.edu at 626-395-6524
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