Fractional form of “0.7 anomaly” in 1D hole systems

We analyze the fractional quantization of the ballistic conductance associated with the light and heavy holes bands in silicon quantum wires. It is shown that the formation of the localized hole state in the region of the quantum point contact connecting two quasi-1D hole leads modifies drastically the conductance pattern. Exchange interaction between localized and propagating holes results in the fractional quantization of the ballistic conductance different from those in electron systems. The value of the conductance at the additional plateaux depends on the offset between the bands of the light and heavy holes, Δ, and the sign of the exchange interaction constant.