Fractional quantization in ac conductance of AlxGa1-xAs capacitors

Minima are found in the ac conductance (100 kHz) of n - GaAs-AlxGa1-xAs-n+-GaAs capacitors at voltages corresponding to fractional fillings, frac13; and frac23;, of the lowest spin-split Landau level of an accumulation layer on n - GaAs. These are the first observations of a fractional quantum effect in which electron motion is perpendicular rather than parallel to the n - GaAsAlxGa1-xAs interface. © 1986 The American Physical Society.