Co distribution in ferromagnetic rutile Co-doped TiO2_2 thin films grown by laser ablation on silicon substrates

Pure rutile Co-doped TiO$_2$ films were fabricated successfully by the conventional pulsed laser deposition technique on silicon substrates from a ceramic target. Under the right fabrication conditions, Co concentration in the films could be almost the same as in the synthesized target, and films under various conditions all are ferromagnetic well above room temperature. Even though Rutherford backscattering spectroscopy measurements show that Co atoms seem to be mostly localized near the surface of the films and less exist in deeper levels, other experimental evidences show that the ferromagnetism does not come from Co segregations but from the Co-doped TiO$_2$ matrix. Rutile Ti$_1-x$Co$_x$O$_2$ thin films grown by a very simple technique on low-price silicon substrates showing Curie temperature (TC) above 400 K appear to be very attractive to applications.Comment: 1 file, 13 pages, 4 figures. to be published in Appl. Phys. Lett. (2003

Élaboration de (La, Sr, Ca, Ba)(Mn, Ru)O3 (étude en diffractométrie, transport, infrarouge et résonance magnétique)

Des manganites dont la structure dérive de la pérovskite idéale ABO3, La0.8Sr0.2-x(Ca,Ba)xMn1-yRuyO3, ont été obtenues par le procédé citrate assisté par un gel de polyacrylamide. L'évolution des propriétés a été étudiée en fonction de trois paramètres : la valence du manganèse reliée au taux de Ru, le rayon ionique sur le site A et le désordre 2A engendré par l'écart type à rA. Les effets antagonistes de rA et de 2A ont été clairement mis en évidence par résonance paramagnétique électronique, mesures de résistivité et de réflectivité infrarouge. L'introduction de Ru diminue le rapport Mn4+/Mn3+ et augmente les distorsions Jahn-Teller. Le domaine ferromagnétique métallique est maintenu dans pour les concentrations étudiées. Deux effets intéressants ont été mis en évidence : un renforcement de la métallicité par la création d'un chemin de conduction Ru-O-Mn et un effet d'impureté qui a été associé à une dispersion des temps de relaxation des moments magnétiques autour du Ru.Manganites witch structure derivates from ideal perovskites ABO3, La0.8Sr0.2-x(Ca,Ba)xMn1-yRuyO3, were obtained using a citrate process assisted by a polyacrylamide network. The evolution of the properties was considered according to three parameters: the manganese valency connected to the Ru content, the average ionic radii on the A site rA and the disorder 2A produced by the lattice mismatch. The antagonistic effects of rA and 2A were clearly showed by electronic paramagnetic resonance, resistivity measurements and infrared reflectivity. Introduction of Ru decreases the Mn4+/Mn3+ ratio and increases the Jahn-Teller distortions. The ferromagnetic metal region is maintained in this range of concentrations. Two interesting effects were highlighted: a support of the metallicity by the creation of a conduction way Ru-O-Mn and an impurity effect which was associated at a relaxation time dispersion of the magnetic moments around Ru.TOURS-BU Sciences Pharmacie (372612104) / SudocSudocFranceF

Magnetic properties of V-doped ZnO thin films

Ferromagnetic V-doped ZnO films were fabricated by the conventional pulsed-laser deposition technique on R-cut sapphire substrates from a ceramic target that was made by sol-gel method. All films are highly crystallized to be wurtzite. V-doped ZnO thin films grown at 600–650 °C show room-temperature ferromagnetism along with a spin-glass-like behavior at low temperatures. It is found that V atoms were distributed very uniformly in the ZnO matrix. However, different growth conditions could result in different values of the saturation magnetic moment, and an increase of the substrate temperature above 650 °C seems to favor a secondary phase, which is antiferromagnetic

Ferromagnetism at room temperature with a large magnetic moment in anatase V-doped TiO_2 thin films

V-doped TiO_2 thin films were grown by laser ablation on LaAlO_3 substrates. In the chosen range of the growth conditions, all V:TiO_2 films have an anatase structure and exhibit semiconducting and ferromagnetic behaviors at room temperature. V:TiO_2 films have a giant magnetic moment and they seem to be far better ferromagnetic than Co/Fe/Ni-doped TiO_2 films. This study has proved that a few percent of V substituting for Ti in TiO_2 can result in a potential diluted magnetic semiconductor

Transparent Cr-doped SnO 2 thin films: ferromagnetism beyond room temperature with a giant magnetic moment

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Transparent Cr-doped SnO 2 thin films: ferromagnetism beyond room temperature with a giant magnetic moment

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Fe- and Ni-doped TiO2 thin films grown on LaAlO3 and SrTiO3 substrates by laser ablation

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Fe- and Ni-doped TiO_2 thin films grown on LaAlO_3 and SrTiO_3 substrates by laser ablation

Room temperature ferromagnetic Fe- and Ni-doped TiO_2 thin films were grown by the laser ablation on both LaAlO_3 and SrTiO_3 substrates. Most of the films are pure anatase, and only the films of Ni content of 3.6% and 4.6% are rutile. Films on LaAlO_3 substrates are more crystallized than films on SrTiO_3 substrates resulting from the lattice mismatch. Our magnetic measurements also suggest that the ferromagnetism in Fe/Ni:TiO_2 films is not due to Fe/Ni segregations but due to Fe/Ni:TiO_2 matrices

Fe- and Ni-doped TiO2 thin films grown on LaAlO3 and SrTiO3 substrates by laser ablation

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Co distribution in ferromagnetic rutile Co-doped TiO2 thin films grown by laser ablation on silicon substrates

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