Structural and transport properties ofGaAs/δ-Mn/GaAs/InxGa1−xAs/GaAs quantum wells

Abstract

We report results of investigations of the structural and transport properties ofGaAs/Ga1−xInxAs/GaAs quantum wells (QWs) having a 0.5–1.8 monolayer (ML) thick Mn layer, separatedfrom the QW by a 3 nm thick spacer. The structure has hole mobility of about2000 cm2 (V s)−1, being by several orders of magnitude higher than in known ferromagnetic two-dimensional(2D) structures. The analysis of the electro-physical properties of these systems is based ondetailed study of their structure by means of high-resolution x-ray diffractometry andglancing-incidence reflection, which allow us to restore the depth profiles of the structuralcharacteristics of the QWs and thin Mn-containing layers. These investigations showthe absence of Mn atoms inside the QW. The quality of the structures was alsocharacterized by photoluminescence spectra from the QWs. The transport propertiesreveal features inherent to ferromagnetic systems: a specific maximum in thetemperature 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 isobserved. The results are discussed in terms of the interaction of 2D-holes and magneticMn ions in the presence of large-scale potential fluctuations related to the randomdistribution of Mn atoms. The AHE values are compared with calculations taking intoaccount the ‘intrinsic’ mechanism in ferromagnetic systems.