Oxygen vacancy-related room temperature ferromagnetism in TiO2 nanohole arrays

Abstract

Room temperature ferromagnetism was observed in hole-like TiO₂ nanostructure arrays prepared by a monolayer colloidal crystal template. The saturation magnetization (M_S) is 0.46 emu g⁻¹ for the as-grown array, which is stronger than that of pristine TiO₂ magnetic semiconductors in other work. It is found that the M_S exhibits a monotonous decrease with increasing annealing temperature. Results show that the ferromagnetism behavior of the TiO₂ nanoarray is related to oxygen vacancies on the surface of nanoparticles, and M_S is determined by the concentration of oxygen vacancies. This work will provide a facile way to fabricate magnetic semiconductor nanoarrays and tailor their ferromagnetism for the application in spin-based nanodevices.