Infrared absorption in a quantum wire in the presence of spin-orbit coupling: a technique to measure different types of spin-orbit interaction strengths

TL;DR

This paper proposes a spectroscopic method to distinguish and measure the strengths of Rashba and Dresselhaus spin-orbit interactions in quantum wires by analyzing the splitting and shifts in absorption peaks.

Contribution

It introduces a novel optical absorption technique to separately quantify Rashba and Dresselhaus spin-orbit coupling strengths in quantum wires.

Findings

Absorption peaks split into a main and satellite peaks due to spin-orbit interactions.

Satellite peaks exhibit red and blue shifts depending on the interaction type.

The method allows separate measurement of Rashba and Dresselhaus strengths.

Abstract

We show that the dominant absorption peak due to inter-subband transition in a gated quantum wire, with two occupied subbands, will split into a main peak and two satellite peaks if both Rashba and Dresselhaus spin-orbit interactions are present. One satellite peak will be red-shifted, and the other blue-shifted. From the relative intensity of either satellite peak, and the magnitude of the red- or blue-shift, we can determine both Rashba and Dresselhaus interaction strengths separately, if we also carry out a Hall measurement to determine the carrier concentration and a quantized conductance step measurement to determine the energy separation between subbands. This method may be a convenient alternative to usual magneto-transport measurements used to measure spin orbit interaction strengths. It is also more powerful because it allows us to measure the strengths of the two types of interactions separately.