1,332 research outputs found
Noise In Nonohmic Regimes Of Disordered Systems
We present here a short review of mainly experimental properties of noise as
disordered systems are driven into non-ohmic regimes by applying voltages of
few volts only. It is found that the noise does not simply follow the
resistance in that the direction of change of noise could be opposite to that
of resistance. It is discussed how this and other properties make the noise a
complementary and incisive tool for studying complex systems, particularly its
dynamic properties. Study of noise in non-ohmic regimes in physical systems is
rather in a nascent stage. Some of the open issues are highlighted.Comment: 9 Pages, 7 figures. Reported in Unsolved Problems of Noise and
Fluctuations: UPoN 2005, Gallipoli, Italy, June 6-10, 200
Stationary Regime of Random Resistor Networks Under Biased Percolation
The state of a 2-D random resistor network, resulting from the simultaneous
evolutions of two competing biased percolations, is studied in a wide range of
bias values. Monte Carlo simulations show that when the external current is
below the threshold value for electrical breakdown, the network reaches a
steady state with a nonlinear current-voltage characteristic. The properties of
this nonlinear regime are investigated as a function of different model
parameters. A scaling relation is found between and , where
is the average resistance, the linear regime resistance and
the threshold value for the onset of nonlinearity. The scaling exponent is
found to be independent of the model parameters. A similar scaling behavior is
also found for the relative variance of resistance fluctuations. These results
compare well with resistance measurements in composite materials performed in
the Joule regime up to breakdown.Comment: 9 pages, revtex, proceedings of the Merida Satellite Conference
STATPHYS2
Low noise constant current source for bias dependent noise measurements
A low noise constant current source used for measuring the noise in
disordered systems in ohmic as well as non-ohmic regime is described. The
source can supply low noise constant current starting from as low as 1 A
to a few tens of mA with a high voltage compliance limit of around 20 Volts.
The constant current source has several stages which can work in a standalone
manner or together to supply the desired value of load current. The noise
contributed by the current source is very low in the entire current range. The
fabrication of a low noise voltage preamplifier modified for bias dependent
noise measurements and based on the existing design available in the MAT04 data
sheet is also described.Comment: 7 pages, 7 figures, to be published in Review of Scientific
Instrument
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