Ferromagnetism at 300 K in spin-coated films of Co doped anatase and rutile TiO2

TL;DR

This study demonstrates that Co-doped TiO2 thin films, prepared via spin-coating and annealed in vacuum, exhibit ferromagnetism at room temperature with Curie temperatures above 350 K, highlighting potential for spintronic applications.

Contribution

It shows that vacuum annealing of spin-coated Co-doped TiO2 films induces strong room-temperature ferromagnetism, a novel approach for magnetic oxide thin films.

Findings

Ferromagnetism observed at 300 K in Co-doped TiO2 films.

Vacuum annealing significantly enhances magnetic moments.

Curie temperature exceeds 350 K in these films.

Abstract

Thin films of Ti1-xCoxO2 (x=0 and 0.03) have been prepared on sapphire substrates by spin-on technique starting from metalorganic precursors. When heat treated in air at 550 and 700 C respectively, these films present pure anatase and rutile structures as shown both by X-ray diffraction and Raman spectroscopy. Optical absorption indicate a high degree of transparency in the visible region. Such films show a very small magnetic moment at 300 K. However, when the anatase and the rutile films are annealed in a vacuum of 1x10-5 Torr at 500 oC and 600 oC respectively, the magnetic moment, at 300 K, is strongly enhanced reaching 0.36 B/Co for the anatase sample and 0.68 B/Co for the rutile one. The ferromagnetic Curie temperature of these samples is above 350 K.