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Using synchrotron x-ray diffraction and reflectivity, we studied the transition from the paramagnetic NiMn phase to the chemically ordered, antiferromagnetic L10 phase of NiMn/Fe19Ni81 thin films deposited on a Si/SiO2 substrate as a function of the annealing temperature. The transformation to a dominating L10-ordered NiMn film takes place between 300 and 400 °C irrespective of the irradiation. This is also consistent with magnetization reversal measurements of the corresponding permalloy layers. The benefit of the ion irradiation is a reduction of the mosaicity for both the NiMn and the permalloy film, and a smoothening of internal interfaces. [ABSTRACT FROM AUTHOR]

Abstract: The A1→L10 phase transition of Fe50Pt50 films, deposited at room-temperature on amorphous SiO2 by dc magnetron co-sputtering at 0.3Pa, was studied with in-situ X-ray diffraction. An almost complete transition characterized by a long-range order parameter S >0.8 is obtained already after a heat treatment at (320±20)°C. A post-deposition He ion irradiation (50keV, 1×1015 −3×1016 cm−2) does not further reduce the transition temperature. Theoretical calculations reveal that, due to the negligible thermalization of the sputtered atoms and reflected ions in the plasma, a considerable fraction of energetic ions and atoms meet the substrate surface. The low transition temperature is explained by the impact of energetic ions and atoms which provoke significant adatom mobility and a decrease of the activation energy for atomic reordering by vacancies. Consequently, using deposition parameters leading to a strong thermalized plasma, the FePt films showed an increase of the transition temperature up to 400°C, a lower S-value (S ≅0.6) and a reduced coercivity. [Copyright &y& Elsevier]

Si-based light emitters will be a key element of future optoelectronics. One of the most promising approaches is Ge implantation into thin SiO[sub 2] films on crystalline Si. This system exhibits a strong violet electroluminescence with a power efficiency up to 0.5% [18], but the mechanism of electrical excitation is not yet fully understood. In this paper the electrical excitation of the luminescence centers is investigated by means of electrical and electroluminescence transient measurements. It is found that the most probable way to excite luminescence centers is the impact excitation by hot electrons. Whereas the injection is explained by trap-assisted tunneling of electrons from the substrate into the oxide, the electrons will be transported via traps or in the SiO[sub 2] conduction band. Furthermore, the electroluminescence rise and decay time is estimated to be of the order of 100 μs. [ABSTRACT FROM AUTHOR]

Abstract: Nickel–Titanium (Ni–Ti) thin film shape memory alloys (SMAs) have been widely projected as novel materials which can be utilized in microdevices. Characterization of their physical properties and its correlation with phase transformations has been a challenging issue. In the present study, X-ray beam diffraction has been utilized to obtain the structural information at different temperatures while cooling. Simultaneously, electrical resistivity (ER) was measured in the phase transformation temperature range. The variation of ER and integral area of the individual diffraction peaks of the different phases as a function of temperature have been compared. A mismatch between the conventional interpretation of ER variation and the results of the XRD data has been clearly identified. [Copyright &y& Elsevier]