Observation of large Zeeman splitting in GaGdN/AlGaN ferromagnetic semiconductor double quantum well superlattices

• Published in: Solid state communications 2012-07, Vol.152 (14), p.1270-1273
• Main Authors: Zhou, YiKai, Almokhtar, Mohamed, Kubo, Hitoshi, Mori, Nobuya, Emura, Shuichi, Hasegawa, Shigehiko, Asahi, Hajime
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; D. Ferromagnetic semiconductor; E. Molecular-beam epitaxy; E. Spintronics; Electron states and collective excitations in thin films, multilayers, quantum wells, mesoscopic and nanoscale systems; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Exact sciences and technology; Magnetic properties and materials; Magnetic semiconductors; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures; Physics; Quantum wells; Studies of specific magnetic materials
• ISSN: 0038-1098; 1879-2766
• DOI: 10.1016/j.ssc.2012.02.026

Symmetric GaGdN/AlGaN (Gd concentration: 2%) and GaN/AlGaN double quantum well superlattices (DQW-SLs) were grown by radio-frequency plasma-assisted molecular-beam epitaxy on GaN (0001) templates. Atomic steps were observed on all the sample surfaces by atomic force microscope. X-ray diffraction θ/2θ scan curves exhibited well-defined satellite structures. Room temperature ferromagnetism was confirmed for the GaGdN/AlGaN DQW-SL samples by using alternating gradient magnetometer. Strong photoluminescence was observed from both GaGdN and GaN QWs at higher energy side of GaN excitonic peak. Magneto-photoluminescence spectra for GaGdN/AlGaN DQW-SL samples showed a large magnetic field dependence of the excitonic energy by applying a magnetic field up to 7T. The observed strong redshift of excitonic PL indicated an enhancement of Zeeman splitting of the free carrier energy levels in magnetic GaGdN/AlGaN DQW-SL. Enhanced g-factor was estimated to be about 60 for GaGdN/AlGaN DQW-SL sample with QW thickness of 1nm. ► Room temperature ferromagnetism was confirmed for the GaGdN/AlGaN superlattices. ► Enhanced Zeeman splitting was observed in magnetic GaGdN/AlGaN superlattices. ► Enhanced g-factor was estimated to be about 60 for the GaGdN/AlGaN sample.