Spin-orbit coupling in Zn0.05Cd0.95O/CdO heterostructures grown by spray pyrolysis

Abstract

This work studies the structural, morphological and electrical properties of a heterostructure, Zn_0.05Cd_0.95O/CdO, comparing them with the films that compose it, CdO and Zn_0.05Cd_0.95O, grown on glass substrate using the spray pyrolysis technique. The heterostructure presented higher crystalline and crystallite size compared to the separate films. The scanning electron microscopy (SEM) images revealed a well-defined interface, thus proving that the heterostructure was formed. In the electrical characterization, both films presented semiconductor-like behavior in resistance in the range of $100K$ to $1.9K$, while the heterostructure presented this behavior up to $3.5K$ and below this temperature a drop in the resistance was observed. This decrease is attributed to the presence of spin-orbit coupling (SOC) that was confirmed in the magnetoresistance (MR) measurements, with only the heterostructure presenting weak antilocalization (WAL) below 4.2 K. This effect was not observed in the individual films, suggesting that it is an intrinsic property of the interface due to the formation of a two-dimensional electron gas (2DEG). For the analysis of the SOC effect, the Hikami Larkin Nagaoka (HLN) model was used, which was fitted to the MR curve of the heterostructure only for the lowest temperature. The parameters obtained with this model were the phase coherence length $L_{\varphi }=\left(142.8\pm 0.1\right)nm$ and the spin-orbit scattering length $L_{so}=\left(232.2\pm 0.1\right)nm$ at $T=1.9K$, indicating that this heterostructure may have application in the field of spintronics.