Defect-induced room temperature ferromagnetism in Cu-doped In2S3 QDs

The practical applications of the existing diluted magnetic semiconductors (DMSs) depend crucially on study aimed at improving their room temperature ferromagnetism. Doping, as an effective method, can modulate the physical properties of semiconductor materials. Herein, we report on the observation of significant RTFM in a III-VI semiconductor compound doped with nonmagnetic impurities, Cu-doped In2S3 quantum dots (QDs) grown by a gas-liquid phase chemical deposition method. The effect of Cu doping on the electronic structures, optical and magnetic properties of In2S3 is studied systematically. UV-vis and photoluminescence (PL) spectra reveal that Cu-doped In2S3 can moderately benefit the optical properties of pristine In2S3. Magnetic measurements show that the pristine In2S3 and Cu-doped In2S3 QDs exhibit obvious RTFM, which is ascribe to the role of intrinsic defects in accordance with bound-magnetic-polaron (BMP) theory. Furthermore, first-principles calculations based on spin density functional theory indicate that In vacancies and their complexes with Cu dopants play a crucial role for the appearance of ferromagnetism. These results suggest that the Cu-doped In2S3 QDs are promising candidates for spintronics and magneto-optics applications.