Observation of room temperature d0 ferromagnetism, band-gap widening, zero dielectric loss and conductivity enhancement in Mg doped TiO2 (rutile + anatase) compounds for spintronics applications

Abstract

Recently, non-magnetic element doped d0 ferromagnetic oxides have been widely studied for their potential spintronics applications. Crystal Structure, elemental color mapping, magnetic, electrical and optical properties of Ti1-xMgxO2 (x ​= ​0, 0.03, 0.06, 0.09 and 0.12) compounds, synthesized by solid-state route were systematically investigated in this paper. X-ray diffraction patterns of these compounds reveal that all Mg-doped TiO2 have been formed in mixed phase of rutile (predominant) and anatase. The anatase phase increases with the increase of the Mg doping concentration. The elemental color mapping using energy dispersive spectroscopy indicates that all elements such as Ti and Mg are distributed uniformly throughout the sample. Ferromagnetism with hysteresis loops is seen in all the compounds, with Curie temperatures above 400 ​K and coercivity values in the range 380–790 ​Oe. The maximum value of saturation magnetization was exhibited by the 6% doped sample. Zero field cooled and field cooled magnetization curves show a bifurcation, which pertains to magnetic irreversibility. The optical band gap of these compounds widens up to 9% of Mg doping and thereafter narrows on further doping. Moreover, these materials show zero loss tangent and an enhancement of dielectric constant with Mg doping. These materials may be useful in magnetic storage, spintronics and optoelectronics applications at high frequency.