Structural and transport properties of GaAs/delta<Mn>/GaAs/InxGa1-xAs/GaAs quantum wells

TL;DR

This study investigates the structural and transport properties of GaAs/delta-Mn/GaAs/InxGa1-xAs/GaAs quantum wells, revealing high hole mobility, absence of Mn in the wells, and ferromagnetic-like transport features such as anomalous Hall effect.

Contribution

It provides detailed structural analysis and transport measurements of Mn-doped quantum wells, demonstrating high mobility and ferromagnetic transport phenomena without Mn incorporation into the wells.

Findings

Hole mobility ~2000 cm²/(V·s)

Presence of anomalous Hall effect up to 100 K

Absence of Mn atoms inside the quantum wells

Abstract

We report results of investigations of structural and transport properties of GaAs/Ga(1-x)In(x)As/GaAs quantum wells (QWs) having a 0.5-1.8 ML thick Mn layer, separated from the QW by a 3 nm thick spacer. The structure has hole mobility of about 2000 cm2/(V*s) being by several orders of magnitude higher than in known ferromagnetic two-dimensional structures. The analysis of the electro-physical properties of these systems is based on detailed study of their structure by means of high-resolution X-ray diffractometry and glancing-incidence reflection, which allow us to restore the depth profiles of structural characteristics of the QWs and thin Mn containing layers. These investigations show absence of Mn atoms inside the QWs. The quality of the structures was also characterized by photoluminescence spectra from the QWs. Transport properties reveal features inherent to ferromagnetic systems: a specific maximum in the temperature dependence of the resistance and the anomalous Hall effect (AHE) observed in samples with both "metallic" and activated types of conductivity up to ~100 K. AHE is most pronounced in the temperature range where the resistance maximum is observed, and decreases with decreasing temperature. The results are discussed in terms of interaction of 2D-holes and magnetic Mn ions in presence of large-scale potential fluctuations related to random distribution of Mn atoms. The AHE values are compared with calculations taking into account its "intrinsic" mechanism in ferromagnetic systems.