Quantum Transport in Nanostructures
We are interested in electron transport in different situations where the quantum (wave) nature of
electrons is important. Two main directions of research are:
Electron Interference
and Electron Interactions in Low-Dimensional Structures.
Metal-to-Insulator Transition.
Coherent
electron waves, scattered by disorder, interfere with each
other. Disorder also modifies the character of the Coulomb interaction
between electrons. Quantum interference and electon-electron
interaction change dramatically electron motion in a low-dimensional
system, so that they can either conduct electricity at zero
temperature (metal) or become localised (insulator).
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Mesoscopic effects in nanostructures.
The conductance of a small sample is not self-averaged but determined by the exact realisation of
the disorder. The conductance becomes unique and fluctuates from sample to sample, and with varying
electron density, magnetic and electric fields. Its measurement allows one to probe individual electron processes
in quantum transport.
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Experimental objects
They are semiconductor transistor structures of different shapes: 2D
layers, 1D wires, and 0D dots. Transistors are tunable experimental
systems where the carrier density is varied by the gate voltage, so
that the transition between different conduction regimes is easily
realised: from diffusive electron motion at high densities (metal), to
hopping and resonant tunnelling at low densities (insulator). New
structures we study are carbon-based: 1D carbon nanotubes and 2D
single-layer graphite (graphene).
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What and how we measure
To preserve phase coherence we perform our experiments at low temperatures, down to 30 mK. We study:
- Resistance and magnetoresistance;
- Compressibiliy (capacitance);
- Shot (current) noise and 1/f (resistance) noise;
- Coulomb drag.
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