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

Abstract

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 $\mathrm{GaAs}/{\mathrm{Al}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{As}$ 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 $0.7\ifmmode\times\else\texttimes\fi{}{2e}^{2}/h.$ Using both pressure and illumination the electron density in the 2DEG was reduced from $2.14\ifmmode\times\else\texttimes\fi{}{10}^{15}{\mathrm{m}}^{\ensuremath{-}2}$ to $0.6\ifmmode\times\else\texttimes\fi{}{10}^{15}{\mathrm{m}}^{\ensuremath{-}2},$ 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 Schr\"odinger-Poisson equation for the heterostructure. There is also a reversal of the persistent photoconductivity effect at high pressures that cannot be accounted for.