Multiple conducting carriers generated in LaAlO3/SrTiO3 heterostructures

TL;DR

This study reveals the coexistence of multiple types of conducting carriers in LaAlO3/SrTiO3 heterostructures, with optical and dc-transport methods highlighting different carrier contributions and mobilities.

Contribution

It demonstrates the presence of more than one type of conducting carrier and compares their contributions using optical and dc-transport measurements.

Findings

Optical spectroscopy reflects high-density carriers.

dc-transport emphasizes high-mobility, low-density carriers.

Low-temperature mobilities differ significantly between methods.

Abstract

We have found that there is more than one type of conducting carriers generated in LaAlO3/SrTiO3 heterostructures by comparing the sheet carrier density and mobility from optical transmission spectroscopy with those from dc-transport measurements. When multiple types of carriers exist, optical characterization dominantly reflects the contribution from the high-density carriers whereas dc-transport measurements may exaggerate the contribution of the high-mobility carriers even though they are present at low-density. Since the low-temperature mobilities determined by dc-transport in the LaAlO3/SrTiO3 heterostructures are much higher than those extracted by optical method, we attribute the origin of high-mobility transport to the low-density conducting carriers.