Phenomenological model for the 0.7 conductance feature in quantum wires

TL;DR

This paper presents a phenomenological model explaining the 0.7 conductance feature in quantum wires, showing strong agreement with experimental data and highlighting the role of the contact potential profile.

Contribution

It introduces a simple phenomenological model for the spin gap in quantum wires that aligns well with experimental observations, advancing understanding of the 0.7 conductance anomaly.

Findings

The model accurately reproduces the conductance feature near 0.7 x 2e^2/h.

The 0.7 feature depends on the potential profile at the contact region.

Microscopic explanations are discussed in relation to the phenomenological model.

Abstract

One dimensional (1D) quantum wires exhibit a conductance feature near 0.7 x 2e^2/h in connection with many-body interactions involving the electron spin. With the possibility of exploiting this effect for novel spintronic device applications, efforts have focused on uncovering a complete microscopic theory to explain this conductance anomaly. Here we present conductance calculations based on a simple phenomenological model for a gate-dependent spin gap that are in excellent agreement with experimental data taken on ultra-low-disorder quantum wires. Taken together the phenomenology and experimental data indicate that the 0.7 feature depends strongly on the potential profile of the contact region, where the reservoirs meet the 1D wire. Microscopic explanations that may under-pin the phenomenological description are also discussed.