Impact of vacuum thermal treatments on the structure and magnetic properties of titanium oxide films doped with Co

Abstract

The structure and magnetic properties of different titanium oxide films doped with magnetic impurities are investigated both in the as-deposited state and after thermal treatments in a vacuum. The samples were characterized by x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), x-ray absorption spectroscopy (XAS) and vibrating sample magnetometry. In the as-deposited films, ferromagnetism was shown to be caused by the formation of magnetic clusters during the deposition. Heating of Ti1−xCoxO2−δ films in a vacuum up to high temperatures and the following quenching thereof result in partial dissolution of the clusters with the magnetic ions being incorporated into the matrix. The low-temperature vacuum annealing leads to an increase of weak ferromagnetism in the semiconductor solid solution.

Electromagnetic waves reflection, transmission and absorption by graphene–magnetic semiconductor–graphene sandwich-structure in magnetic field: Faraday geometry

“…Properties of diluted magnetic semiconductor Ti 1−x Co x O 2− may change significantly depending on the method of preparation. It may have a high Curie temperature ∼ 600 K [38], the charge carriers concentration usually is from ∼ 10 18 cm −3 to ∼ 10 22 cm −3 [39], electric resistance can vary from 10 −4 to 10 6 Ohm•cm [40,41], saturation magnetization could be about 10 kA/m [42], data on FMR research of this material, unfortunately, is absent. For this data ω p ∼ 10 14 − 10 16 s −1 , ν ∼ 10 11 − 10 18 s −1 .…”

Room Temperature Ferromagnetic Semiconductor Rutile Ti1-xCoxO2-δEpitaxial Thin Films Grown by Sputtering Method

“…The sputtering methods have been tried to grow Ti 1Àx Co x O 2À films so far, but only magnetization measurement was reported without examining presence of ferromagnetically spin polarized carriers via magneto-optical and anomalous Hall effects and so on. [14][15][16][17][18][19][20] Some of those films were subject to the magnetic precipitations or the lack of electrical conductivity, hence it is difficult to examine fundamental properties.…”