Fractional quantization of ballistic conductance in 1D hole systems

TL;DR

This paper investigates fractional quantization of ballistic conductance in 1D hole systems, revealing how localized hole states and exchange interactions lead to unique conductance plateaux different from electronic systems.

Contribution

It introduces a model showing how localized hole states and exchange interactions cause fractional conductance quantization in 1D hole systems, depending on band offsets and interaction sign.

Findings

Fractional conductance plateaux depend on band offset  and exchange interaction sign.

Ferromagnetic exchange yields plateaux at 7e^2/4h, 3e^2/h, 15e^2/4h.

Antiferromagnetic exchange results in plateaux at e^2/4h, e^2/h, 9e^2/4h.

Abstract

We analyze the fractional quantization of the ballistic conductance associated with the light and heavy holes bands in Si, Ge and GaAs systems. 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 electronic systems. The value of the conductance at the additional plateaux depends on the offset between the bands of the light and heavy holes, \Delta, and the sign of the exchange interaction constant. For \Delta=0 and ferromagnetic exchange interaction, we observe additional plateaux around the values 7e^{2}/4h, 3e^{2}/h and 15e^{2}/4h, while antiferromagnetic interaction plateaux are formed around e^{2}/4h, e^{2}/h and 9e^{2}/4h. For large \Delta, the single plateau is formed at e^2/h.