Band gap tailoring and enhanced ferromagnetism in Yb doped SrWo4 scheelite structured system

Abstract

Room temperature ferromagnetism and enhanced optical property of Yb doped SrWO4 compounds have been investigated for the importance in the field of spintronics. Pristine and Yb doped SrWO4 compounds were synthesized by simple chemical precipitation method. Powder X-ray diffraction analysis reveals the scheelite type tetragonal structure of all the prepared compounds. The crystallite size and lattice strain was calculated by Williamson–Hall plot. The local structural disorder of the compounds was investigated by Laser Raman spectroscopy and it was found that the local disorder induced by the dopant leads to alteration in Raman active modes of Yb doped SrWO4 compounds. The formation of microsphere and platelets like shapes of particulate system was examined by electron microscopy techniques. The evidences for oxygen vacancy and oxidation states of elements present in the compounds were analyzed by X-ray photoemission spectroscopy. In UV–Vis spectra, distinctive shift of absorption edge was observed exclusively for all the Yb doped SrWO4 compounds. The presence of defective states with prominent blue and green emission of the compounds was investigated by photoluminescence spectroscopy. Magnetization study reveals that the pristine SrWO4 compound exhibits unsaturated ferromagnetic behaviour, whereas all the Yb doped SrWO4 compounds demonstrates saturated ferromagnetic behaviour. The enhancement of magnetization and ferromagnetic ordering of the compounds has been explained in terms of carrier-induced Ruderman–Kittel–Kasuya–Yosida interaction theory. Hence, from the present investigation it was observed that the doping of Yb in SrWO4 will yields a new kind of multifunctional material for fabricating magneto-optical and electronic devices.