Carrier mediated ferromagnetism in Cr doped SrTiO 3 compounds

TLDR: In this paper, powder X-ray diffraction (XRD) studies reveal the simple cubic perovskite structure of all the prepared compounds and the grain size and lattice strain of the compounds were estimated from the powder XRD pattern which evidences the incorporation of Cr in SrTiO3 system.

Abstract: The carrier doped ferromagnetism in SrTiO3 compounds has been investigated for the importance in the field of multiferroics and spintronics. Polycrystalline pure and Cr doped SrTiO3 compounds were synthesized by glycol assisted sol–gel method. Powder X-ray diffraction (XRD) studies reveal the simple cubic perovskite structure of all the prepared compounds. The grain size and lattice strain of the compounds were estimated from the powder XRD pattern which evidences the incorporation of Cr in SrTiO3 system. The local order and disorder parameter of the compounds was investigated by laser Raman spectroscopy. The change in particles to rod like surface morphology while increasing Cr doping concentration was examined by scanning electron microscope and transmission electron microscopy. The enhancement of oxygen vacancy while increasing Cr doping concentration in SrTiO3 system and reduction in Ti4+ to Ti3+ states was identified by X-ray photoelectron spectroscopy. The UV–Vis absorption spectra evidence the distinctive shift of absorption edge exclusively for Cr doped SrTiO3 compounds. Photoluminescence (PL) spectra of the compounds reveal defective states and decrease in PL intensity due to the influence of Cr in SrTiO3. Electron paramagnetic resonance analysis of Cr doped compounds reveals the paramagnetic nature of the dopants. The magnetization studies of all the prepared compounds emphasis carrier mediated diamagnetic to ferromagnetic phase transition in due with the presence of carriers induced by Cr. It is also evident that the highest dopant concentration of Cr in SrTiO3 system exhibits reversal ferromagnetism. The enhancement of magnetization and ferromagnetic ordering has been understood in terms of carrier-mediated Ruderman–Kittel–Kasuya–Yosida interaction theory. The present work also demonstrates the influence of surface morphology on the occurrence of ferromagnetism in Cr doped SrTiO3 compounds.