Ashoori Group Homepage

Welcome to the Ashoori Group homepage.

Our mission is to create and exploit specialized methods of sensing electron charges to reveal and demystify the subtle quantum mechanical behavior of correlated electrons in materials.

To learn more about what we do, feel free to browse our website using the navigation bar on the left, or look at our overview.

Recent Ashoori Group News

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Groundbreaking New Quantum Well Designs

A new wafer with a wider quantum well than we've used previously has begun providing fantastic new data. Single atom fluctuations in the width of the quantum well broaden TDCS features in energy. With the wider quantum well, these width variations are less important. The new spectra reveal quantum Hall physics in astounding detail, as shown in the data taken at 1 Tesla above (compare with that in our recent Nature paper. At higher fields, we are beginning to understand how the fractional quantum Hall effect reveals itself in the single particle spectrum, while at lower fields we're pinning down the properties of a previously unobserved coupled electron-plasmon excitation.

Tunneling Spectroscopy in the News

Our recent TDCS work (below) has been well received. Charles Day, with Physics Today, produced an excellent writeup in "Search and Discovery". This made the cover of their Japenese affiliate Parity (as shown to the right). Anne Trafton at MIT's press office also produced an extraordinarily understandable summary, including photos of the new dilution refrigerator we're moving the experiment into. A shorter version of this appeared in MIT's Tech Talk.

"High-resolution spectroscopy of two-dimensional electron systems", Nature 448, 176-179 (12 July 2007).

By probing the single-particle spectrum of a two-dimensional electron gas, we reveal the intricate and beautiful energy structure far from the Fermi surface. The measured spectra show a host of different physical phenomena, making them a fantastic resource for understanding these complex systems

For an overview, you should look at this press release. For more information, have a look at our capacitance spectroscopy page, Oliver's simulations page, or his home page

"Imaging Transport Resonances in the Quantum Hall Effect", Physical Review Letters 95 136804 (2005)

People have long understood that localization plays a fundamental role in the quantum Hall effect. However, the microscopic nature of the localized states is inaccessible to bulk transport measurments: what these localized states actually are is still a mystery. In our work, we use a charge-sensitive scanning probe to measure the transport properties of localized states in the quantum Hall effect on a microscopic scale.

To learn more, have a look at our SPM Imaging page, or Gary Steele's thesis.

Gary's thesis is quite large; if you have a slow connection, you might look at this version with compressed images.