A.F. Cabrera

APPEARANCE OF ROOM-TEMPERATURE FERROMAGNETISM IN CU-DOPED TIO2-DELTA FILMS

In recent years there has been an intense search for room temperature ferromagnetism in doped dilute semiconductors, which have many potentially applications in spintronics and optoelectronics. We report here the unexpected observation of significant room temperature ferromagnetism in a semiconductor doped with nonmagnetic impurities, Cu-doped TiO

Mössbauer identification of μ-type metastable phase as the main magnetic component in Nd60Fe30Al10 melt spun alloys

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Ferromagnetism in doped TiO2 thin films prepared by PLD

thin films grown by Pulsed Laser Deposition. The magnetic moment, calculated from the magnetization curves, resulted surprisingly large, about 1.5

Study of Magnetic Materials by Mössbauer Thermal Scans. Application to Nanocrystalline Systems

\mu_B

Mössbauer thermal scan study of a spin crossover system

per Cu atom. A large magnetic moment was also obtained from ab initio calculations using the supercell method for TiO

Compressive Mechanical Properties of Nanostructured Intermetallic Alloys Al3Ti-X (X = Mn or Fe)

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Thermal Evolution of Fe65Ni20Nb6B9 Nanocrystalline Metastable Alloy

with Cu impurities, but only if an oxygen vacancy in the nearest-neighbour shell of Cu was present. This result suggests that the role of oxygen vacancies is crucial for the appearance of ferromagnetism. The calculations also predict that Cu doping favours the formation of oxygen vacancies.

Effects of coexisting spin disorder and antiferromagnetism on the magnetic behavior of nanostructured (Fe79Mn21)1−xCux alloys

Abstract The local atomic arrangements and the nanoscopically dispersed phases in melt spun Nd 60 Fe 30 Al 10 alloys are investigated by Mōssbauer spectroscopy. It is found that the hard magnetic properties of these alloys are likely to be related to the presence of clusters of a metastable crystalline μ-type phase.

Mössbauer Study of Nd-Fe-Al Nanocomposites

Transition-Metal-doped TiO2 thin films, with nominal composition Ti0.9TM0.1O2-δ (TM = Mn, Fe, Co, Ni, Cu), were grown by pulsed laser deposition (PLD), in order to study the role of dopants in the origin and significance of room temperature ferromagnetism in these systems. The crystallographic structures and their magnetic properties were characterized and the experimental results are compared to ab-initio calculations previously reported. The films are ferromagnetic at room temperature in the cases of Fe, Co, Ni and even Cu impurities, but not in the case of Mn doping. Our results support the hypothesis that oxygen vacancies play a key role in the origin of magnetism in doped TiO2 films, and can explain the diversity of magnetic moments observed experimentally for films grown under different conditions.

Hyperfine Study of Mechanically Induced Transformations in Solids

Mossbauer thermal scans (2 K/min) have been applied to the classical amorphous finemet-type precursor Fe 73.5 Si 13.5 Nb 6Cu 1B9 alloy. They allowed the determination of the ordering temperatures of the amorphous phase before (T C = 624 K) and after partial (T C = 674 K) and complete (T C = 595 K) crystallization. The existence of three well differentiated temperature regions is observed, corresponding to the ferro to paramagnetic transition of the amorphous, nanocrystallization of bcc Fe(Si) and the ferro to superpara or paramagnetic transition of the crystalline phase. The crystallization kinetics at 763 K and 805 K was studied by two different approaches. At 763 K spectra were recorded every two hours up to a total time of 117 h. At 805 K scans were used due to the much higher transformation rate. Both results were analized with theoretical contributions representing the amorphous, very small crystals or embryos and grown up crystals. The evolution of their relative abundances obtained with the two approaches was consistent. The embryo nucleation was almost completed after two and eight hours at 763 and 805 K, respectively.