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Physics and Astronomy

Quantum Systems and Nanomaterials Group

Quantum transport in nanostructures laboratory
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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).


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.


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).


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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