Xiaoyan Shi

Conductance noise in an out-of-equilibrium two-dimensional electron system

A study of the conductance noise in a two-dimensional electron system (2DES) in Si at low temperatures (T) reveals the onset of large, non-Gaussian noise after cooling from an equilibrium state at a high T with a fixed carrier density n_s. This behavior, which signifies the falling out of equilibrium of the 2DES as T->0, is observed for n_s<n_g (n_g - glass transition density). A protocol where density is changed by a small value \Delta n_s at low T produces the same results for the noise power spectra. However, a detailed analysis of the non-Gaussian probability density functions (PDFs) of the fluctuations reveals that \Delta n_s has a qualitatively different and more dramatic effect than \Delta T, suggesting that \Delta n_s induces strong changes in the free energy landscape of the system as a result of Coulomb interactions. The results from a third, waiting-time (t_w) protocol, where n_s is changed temporarily during t_w by a large amount, demonstrate that non-Gaussian PDFs exhibit history dependence and an evolution towards a Gaussian distribution as the system ages and slowly approaches equilibrium. By calculating the power spectra and higher-order statistics for the noise measured over a wide range of the applied voltage bias, it is established that the non-Gaussian noise is observed in the regime of Ohmic or linear response, i.e. that it is not caused by the applied bias.

Effective two-dimensional thickness for the Berezinskii-Kosterlitz-Thouless-like transition in a highly underdopedLa2−xSrxCuO4

The nature of the superconducting transition in highly underdoped thick films of La

Far infrared edge photoresponse and persistent edge transport in an inverted InAs/GaSb heterostructure

_{2-x}

Impact of the modulation doping layer on the ν = 5 / 2 anisotropy

Sr

Giant supercurrent states in a superconductor-InAs/GaSb-superconductor junction

_x

McMillan-Rowell like oscillations in a superconductor-InAs/GaSb-superconductor junction

CuO

History dependent magnetoresistance in lightly doped La2−xSrxCuO4 thin films

_4

Evidence For Correlated Dynamics Near The Berezinskii-kosterlitz-thouless-like Transition In Highly Underdoped La2-xsrxcuo4

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Low-temperature resistance noise spectroscopy as a probe of the superconducting transition in underdoped La2-xSrxCuO4

x=0.07

Search for Majorana fermions in topological superconductors.

and 0.08) has been investigated using the in-plane transport measurements. The contribution of superconducting fluctuations to the conductivity in zero magnetic field, or paraconductivity, was determined from the magnetoresistance measured in fields applied perpendicular to the CuO