Tuning the electron transport properties of a one-dimensional constriction using hydrostatic pressure

Hydrostatic pressure and illumination have been used to investigate electron transport through a clean one-dimensional constriction in a deep two-dimensional electron gas (2DEG) formed at a $\mathrm{GaAs}/{\mathrm{Al}}_x{\mathrm{Ga}}_{1-x}\mathrm{As}$ interface. Up to 20 quantized conductance steps were observed at integer multiples of ${2e}^2/h,$ as well as a clear additional step (the “0.7 structure”) at approximately $0.7\times {2e}^2/h.\mathrm{}$ Using both pressure and illumination the electron density in the 2DEG was reduced from $2.14\times {10}^{15}{\mathrm{m}}^{-2}$ to $0.6\times {10}^{15}{\mathrm{m}}^{-2},$ and a shift in the conductance of the “0.7 structure” towards the spin-split value of $e^2/h$ was observed. The density measurements are compared to calculations of the 2D electron density as a function of pressure, obtained by solving the Schrödinger-Poisson equation for the heterostructure. There is also a reversal of the persistent photoconductivity effect at high pressures that cannot be accounted for.