Effect of Mg-doping in tailoring d0 ferromagnetism of rutile TiO2 compounds for spintronics application

Abstract

d0 ferromagnetism in non-magnetic element-doped oxide materials has caught the attention of researchers due to their promising application in spintronics devices. In a search of finding novel materials exhibiting d0 ferromagnetism, we have studied the Mg-doped TiO2, i.e., Ti1-xMgxO2 (x = 0, 0.02, 0.04, and 0.06) compounds, synthesized by solid-state reaction route method. Single phase of tetragonal rutile structure is observed by X-ray diffraction (XRD) patterns for all compounds. The samples show uniform morphology with particles size ranging from 150 to 200 nm, as per the scanning electron microscopy observations. The magnetic properties investigation by SQUID magnetometer indicates paramagnetic behavior in undoped TiO2 and 2% Mg-doped TiO2, whereas the Ti0.96Mg0.04O2 compound exhibits ferromagnetism embedded in a paramagnetic phase. However, 6% Mg-doped TiO2 exhibits ferromagnetism with a transition temperature of 180.2 K. Further, magnetization vs. temperature curves measured under zero-field, and field-cooled condition for x = 0.06 sample reveal low-temperature magnetic irreversibility, which can be ascribed to the competing antiferromagnetic and ferromagnetic phases. The hysteresis curve with a coercivity of 6515 Oe at 5 K along with domain wall pinning and zero-field-cooled exchange-bias behavior are observed for x = 0.06 sample from the M–H curves.