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The 1/f Spectrum: A Not-So-Fundamental Noise Distribution?<br><b>Speaker: Cagliyan Kurdak (UM Physics)</br></b>

Wednesday, October 5, 2011
12:00 AM
340 West Hall

Speaker: Cagliyan Kurdak (UM Physics)

It is well known that most semiconducting, metallic, and superconducting systems exhibit excess noise with a 1/f-type noise spectrum at low frequencies. Despite earlier theoretical work that tried to come up with a universal framework for 1/f noise, we now know that there are no fundamental processes that are responsible for the presence of 1/f noise in these systems. The processes that contribute to the 1/f noise are specific to each system and, in principle, can be fully eliminated. There are a few systems, where the 1/f noise was suppressed by many orders of magnitude as a result of focused efforts on improving material quality. Unfortunately, despite its significance, the 1/f noise in most materials has not been studied in detail. In this talk, I will focus on different material systems where transport is dominated by tunneling of electrons between localized levels. First, I will discuss 1/f noise in high quality GaAs/AlGaAs heterostructures with a two-dimensional electron gas. This system exhibits novel states of matter, such as fractional quantum Hall liquids, which are known to have unusual excitations that carry fractional change and obey fractional statistics. Recently, we have focused our studies on the deep insulation regime of integer and fractional quantum Hall liquids, a transport regime not accessible by ordinary transport measurements. We have explored the charge dynamics, including 1/f noise, in this regime by using single electron transistors. I will discuss our new strategies to study fractional statistics that can be performed by further reduction of 1/f noise in this system. Second, I will discuss 1/f noise in two material systems, thiol-coated gold nanoparticles and ultra-thin metallic films, that are technologically important for sensing applications. I will discuss our current understanding of 1/f noise in these systems.