Measurements of cyclotron resonance of the interfacial states in strong spin-orbit coupled 2D electron gases proximitized with aluminum

TL;DR

This study uses high-precision THz spectroscopy to probe the interfacial electronic states in InAs/InGaAs heterostructures with aluminum overlayers, revealing key properties of the 2DEG despite the thick metallic layer.

Contribution

It demonstrates the ability to characterize interfacial states in hybrid 2DEG systems with aluminum layers using THz spectroscopy, providing detailed band parameters.

Findings

Observation of cyclotron resonance despite thick aluminum layer

Extraction of effective mass, charge density, and scattering times of 2DEG

Insights into the electronic properties of hybrid heterostructures

Abstract

Two-dimensional electron gasses (2DEG) in InAs quantum wells proximitized by aluminum are promising platforms for topological qubits based on Majorana zero modes. However, there are still substantial uncertainties associated with the nature of the electronic states at the interfaces of these systems. It is challenging to probe the properties of these hybridized states as they are buried under a relatively thick aluminum layer. In this work, we have investigated a range of InAs/In$ _{1-\text{x}} $Ga$ _\text{x} $As heterostructures with Al overlayers using high precision time-domain THz spectroscopy. Despite the thick metallic overlayer, we observe a prominent cyclotron resonance in the magnetic field that can be associated with the response of the interfacial states. Measurements of the THz range complex Faraday rotation allow the extraction of the sign and magnitude of the effective mass, the density of charge carriers, and scattering times of the 2DEG despite the close proximity of the aluminum layer. We discuss the extracted band parameters and connect their values to the known physics of these materials.