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In order to investigate effect of Ni layer thickness on microstructure and magnetic properties of Si/Ni multiyers, a series of Si/Ni multilayers were deposited at ambient temperature (300K) using dc-magnetron sputtering system. XRD and HRTEM data shows that Si layer is amorphous whereas Ni layer is nanocrystalline in nature with a strong texture along Ni (111) plane. In-plane magnetic measurements have been done with the application of 50 kOe external magnetic field. Magnetization data shows that there is an increasement in saturation magnetization (MS) value towards bulk value of Ni as we increase Ni layer thickness and getting saturated for tNi ≥ 80 Å. The magnetization data also shows a soft magnetic behavior since coercivity of the samples was found to be in the range of 5Oe to 50 Oe and saturation field up to 1000 Oe which is too small. [ABSTRACT FROM AUTHOR]

The Fe3O4 thin films of 2000Å thickness have been grown at room temperature by dc magnetron sputtering technique and their structural and magnetic properties are studied. The structural study shows that the film is random polycrystalline with no preferred orientation.The isothermal in-plane magnetization measurement performed at various temperatures shows a consistent increase in the coercivity (HC) and exchange bias field(HEB)as the temperature lowered, with a significant increase below 100K.The occurrence of small exchange bias indicates the existence of a non-negligible exchange coupling between the core spins and surface spins of the Fe3O4 grains. The ZFC-FC measurements show that samples are having a wide particle size distribution, along with the existence of stronger interaction between the nearby Fe3O4 grains. [ABSTRACT FROM AUTHOR]

In this article, DyxFe100-x nanogranular (15 ≤ x ≤ 25) thin films have been prepared at ambient temperature by dc magnetron sputtering. The correlation between the microstructure, magneto transport and magnetization properties is discussed. The grain size of Dy (Dysprosium) and Fe (Iron) was measured to be about 2 to 3nm, respectively and the distribution of grains was homogenous throughout the sample. The magnetoresistance is sensitive to microstructural changes (particle size as well as Dy concentration). At the room temperature, the magnetoresistance [MR %] increased from 0.2 to 2.2 with increase in atomic concentration of Dy from x = 15 to 25 and we obtained maximum 2.2 MR [%] for x = 25 in this series of samples. The magnetization studies have revealed that all the samples are superparamagnetic (SPM) at room temperature. [ABSTRACT FROM AUTHOR]

In this article, we report the systematic studies and correlations of the microstructural, magnetotransport and magnetic properties of Dy28Fe72 granular thin film, which has been prepared by dc magnetron sputtering at room temperature. The structural properties showed that the distribution of grains was uniform throughout the film and the average grain size of Fe and Dy particles was measured to be ~ 2 nm. The magnetoresistance [MR] increased from 3 to 18 % with decrease in temperature from T = 300 to 4.2 K and we have obtained a maximum of 18 % of MR at T = 4.2 K. The MR and magnetization curves have not saturated even for very high fields (H = 9 Tesla) and at all temperatures which was essentially due to the superparamagnetic (SPM) particles. SPM nature of the film was also inferred by corroborating the field dependence of magnetization and MR. [ABSTRACT FROM AUTHOR]

The structural and the temperature-dependent exchange bias properties of room temperature reactive sputtered Fe3O4 (150 nm) thin films are studied. The structural study shows that the films are polycrystalline with no preferred orientation. The exchange bias measurement performed at various temperatures shows a consistent increase in the magnitude of exchange bias field (HEB) as the temperature is lowered from 300 K, and showing a significant increase at low temperatures, which reaches a value of HEB = 190 Oe at 2 K. The presence of exchange bias effect is mainly due to the existence of a non-negligible exchange coupling between the core spins and the surface spins of Fe3O4 grains. [ABSTRACT FROM AUTHOR]

In the present study, the structural and magnetic properties of the Fe70Dy30 thin films are investigated. The Fe70Dy30 thin film with a thickness of 250 Å is fabricated using a dc magnetron sputtering system. Structural and temperature dependent magnetic properties indicate the granular nature of the film. The nonsaturation of the magnetization curves even at high fields of 50 kOe and the obtained very low coercivity in the temperature range 50 – 300 K reveal that films are superparamagnetic (SPM). The decreasing blocking temperature (Tb) with increasing an external magnetic field in temperature dependent magnetization curves are exposed qualitatively. [ABSTRACT FROM AUTHOR]

The Fe1-xO thin films of various iron deficiencies (x) have been grown at ambient temperature by reactive dc magnetron sputtering technique and their structural and magnetic properties are studied. The structural study shows that the films are polycrystalline. As the iron content (1-x) varies from 0.924 to 0.855 a clear consistent change in the preferential orientation of the grains from [111] to the [200] direction is observed. The magnetization measurements show the possible existence of small superparamagnetic defect clusters at 300 K and large spinel-type defect clusters below the Neel temperature. [ABSTRACT FROM AUTHOR]