NONUNIVERSAL CONDUCTANCE QUANTIZATION IN QUANTUM WIRES

We have measured the transport properties of high-quality quantum wins fabricated in GaAs-AlGaAs by using cleaved edge overgrowth. The low t emperature conductance is quantized as the electron density in the wir e is varied. While the values of the conductance plateaus are reproduc ible, they deviate from multiples of the universal value of 2e(2)/h by as much as 25%. As the temperature or de bias increases the conductan ce steps approach the universal value. Several aspects of the data can be explained qualitatively using Luttinger liquid theory although the n remain major inconsistencies with such an interpretation.