Metal-Insulator Transition in Quench-Condensed<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Al</mml:mi></mml:mrow><mml:mrow><mml:mi>x</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Ge</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math>: "Scaling" and Tunneling Experiments

We report on the metal-insulator transition of quench-condensed ${\mathrm{Al}}_{x}{\mathrm{Ge}}_{1\ensuremath{-}x}$. The transition is obtained either by variation of $x$ or by low-temperature annealing (amorphous-relaxation-like process). This last approach gives a straightforward illustration of the scaling theory of localization and information about the critical behavior. Tunneling measurements of the correlation gap $\ensuremath{\Delta}$ allow a comparison with other materials and show strong electron interactions in this highly disordered system.

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