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'Nano' Implies Nonlinear Dynamics

One thing that we who have worked in the nano area for the past 20 years keep claiming is that new properties and opportunities arise from materials crafted at the nanometer scale. One of the major changes is that the response of materials to stimuli becomes increasingly nonlinear, and that leads to a completely new set of dynamical properties.

I will show how a single nanoscale device can be a DC-voltage controlled oscillator with periodic, chaotic, and coupled-oscillator modes, and how this behavior can be utilized in a neuromimetic circuit for computation. In the process, I will resolve a 55 year old physics conundrum through experimental data and using Leon Chua’s nonlinear dynamical circuit model to show that a single device can have regions inside it with two different current densities flowing simultaneously, and thus behave dynamically as two coupled devices. This occurs because of a temperature-driven instability, or negative differential resistance, that bifurcates to form two locally stable regions with different current densities in a process similar to a spinodal decomposition of a metastable homogeneous liquid.

This may actually be a common occurrence in modern semiconductor devices, and will require a significant change to the methods presently used for modeling current density and electric field characteristics, which may in fact be quantitatively correct on average but yield a qualitatively incorrect nanoscopic picture of current flow.

Speaker: Stan Williams, HP Labs (emeritus)

Friday, 11/09/18

Contact:

Website: Click to Visit

Cost:

Free

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Hearst Memorial Mining Building

UC Berkeley
Room 390
Berkeley, CA 94720