Giant magnetoresistance (GMR) behavior in electrodeposited NFe/Cu/Ni multilayered (ML) structures is investigated as a function of non-magnetic (Cu) and ferromagnetic (Fe and Ni) layers' thicknesses. ...Detailed structural and magnetic analyses of the ML structures are studied before looking into the GMR behavior. Structural analyses reveal that all peaks are well matched with Ni (face-centered cubic) being the top most layer during ML deposition. Shifting of preferred orientation, between (220) and (111) planes, is observed with the thickest layer of copper spacer. Refined structural parameters are calculated and details of fittings are discussed with reference to layer thicknesses. Crystallite size, dislocation density, stacking fault probability, and strain all show oscillatory behavior with variation in thicknesses. Magnetic behavior shows strong dependence of magnetization on thickness of each layer. Saturation magnetization (<inline-formula> <tex-math notation="LaTeX">M_{s}) </tex-math></inline-formula> increases up to a value of 10.12 emu/cm 3 with increasing Fe and Ni layer thicknesses. Whereas, oscillatory behavior of magnetization is observed with variation in Cu layer thickness. Magnetoresistance (MR) measurements show oscillatory GMR behavior as a function of intervening layer thickness. Highest value of GMR ~12% is observed at a Cu layer thickness of 9.6 nm. Structural, magnetic, and MR properties of NFe/Cu/Fe are observed on the basis of variation of thicknesses of non-magnetic (Cu) and ferromagnetic (Fe and Ni) layers. It is observed that layer thicknesses play a dominant effect on the nature (i.e., oscillatory) and on the value of GMR.
•One DLC and three multilayer DLC:Mo thin films were deposited on Si substrate.•Surface roughness and Urbach energy increase linearly as Mo content increases.•Refractive index and optical band gap ...decrease exponentially with Mo addition.•Electrical resistivity decreases exponentially as Mo content increases.•Crystallite size of Mo particles increases exponentially with Mo concentration.
Off-axis pulsed laser deposition technique was used to deposit a diamond-like carbon (DLC) thin film and three multilayer DLC:Mo thin films of various compositions on p-type Si (111) substrate at room temperature keeping the DLC content constant. Excimer laser was used to ablate graphite and Mo targets in a vacuum of ∼10−5mbar, whereas the p-type Si (111) substrate was placed downside the target at a distance of 1cm in off-axis PLD geometry. Morphological, structural, optical, and electrical characteristics of the deposited thin films were then investigated. SEM images of the thin films show that surface roughness increases as Mo content in the film increases. XRD patterns of DLC:Mo thin films rule out any carbide formation. Both crystallite size of Mo particles and film thickness increase whereas microstrain decreases with the increase in Mo content. Moreover, both refractive index and indirect optical band gap decrease exponentially while Urbach energy increases linearly with the increase in Mo content. Electrical resistivity of the thin films has been found to follow an exponential decay with the increase in Mo content in multilayer DLC:Mo thin films.
We report the use of pulsed laser deposition (PLD) to grow manganese oxide thin films at a fixed low oxygen pressure at different temperatures on silicon (1 0 0) substrates. Structural properties of ...the thin films were examined using x-ray diffraction and Fourier transform infrared spectroscopy. Surface morphology and topography of the films was determined using atomic force microscopy and optical microscopy, while optical properties of the thin films were studied using spectroscopic ellipsometry. It was found that PLD is a convenient technique to deposit different phases of manganese oxide by tuning the deposition temperature. All measured physical properties such as morphology, topography, crystallite size, and optical band gap were clearly dependent on the substrate temperature chosen.
► Novel studies on effect of deposition temperature on structural, surface, optical and magnetic properties have been presented in this article. ► At higher substrate temperatures, single crystal ...like growth is observed along with smooth surface profile. ► Optical properties are considerably modified. ► At higher substrate temperatures, films show ferromagnetic character.
The objective of this work is to study the influence of deposition temperature on structural, surface, optical and magnetic properties of the Al doped CdO thin films prepared by pulsed laser deposition (PLD) technique. KrF excimer laser (
λ
=
248
nm,
τ
l
=
20
ns,
ν
=
10
Hz,
ϕ
l
=
2.5
J/cm
2) was employed for the deposition of thin films. It is observed by XRD results that films grown at room temperature and 100
°C show preferential growth along (1
1
1) and (2
0
0) directions while high temperatures (200–400
°C) lead to preferential growth along the (2
0
0) direction only. The optical constants (
n,
k,
α, and optical band gap energy) of films measured by spectroscopic ellipsometry show strong dependence upon deposition temperature. M–H loop of films, measured by vibrating sample magnetometer, deposited at 25
°C and 100
°C show paramagnetic nature while films deposited at temperatures (200–400
°C) exhibit ferromagnetic character. Scanning electron micrographs show degraded elongated grains at lower deposition temperatures, while smooth and compact surface is observed for films deposited at higher deposition temperatures.
Anodic aluminum oxide templates with pore diameter of 40nm and inter pore separation of 100nm are prepared by two step anodization in 0.3M oxalic acid solution. These templates are used to fabricate ...dc-deposited Co nanowires at different pH values of acidic bath. Continuous and densely packed nanowires having length ~8µm are observed. The hcp configuration appeared at moderate and high pH whereas both fcc and hcp phases are observed at low pH. However the crystallinity distorted at high pH due to formation of polycrystalline structure of cobalt nanowires. Alignment of easy-axis of nanowires can be tailored by varying pH of solution.
•Variation in the structure of dc deposited cobalt nanowires can be obtained by varying pH of acidic bath.•The hcp structure is stable at room temperature with low voltage deposition for electrodeposited Co nanowires. Co with fcc structure, is stable at temperatures above 422°C or at pH<3 with high potential.•The hcp (100) plane is obtained with pH~3.5 and (101) is stable at pH~5.5 due to variation in temperature inside the pores with respect to the pH.•Alignment of easy-axis of nanowires can be tailored by varying pH of solution.
•Manganese oxide thin films deposited using pulsed laser deposition technique•Temperatures was the variable (500 °C, 600 °C, 700 °C and 800 °C) and gas pressure was fixed.•Mn3O4 phase of MnO grown at ...800 °C with traces of Mn2O3 at lower deposition temperature.•Band gap .21 eV, 2.23 eV, 2.09 eV and 2.35 eV calculated using Kubelka-Munk Function.
Tetragonal Mn3O4 phase of manganese oxide with traces of cubic Mn2O3 was grown on p-type silicon (100) using pulsed laser deposition technique under different deposition temperatures ranging from 500 °C to 800 °C. Structural features and presences of different phases in thin films were obtained from X-ray Diffraction (XRD). The XRD pattern reveal the transformation of multi-phase tetragonal Mn3O4 and cubic Mn2O3 into single phase Mn3O4 at higher deposition temperature. As a result, the defect density reduced and crystalline quality improved. Optical band gap increased in single phase manganese oxide film, measured using UV-Vis Spectroscopy. A consistent increase in optical band gap, measured using Kubelka-Munk function, was observed in thin film samples with maximum value of 2.35 eV at 800 °C, a pre-requisite for many opto-electronics applications.
Magnetic and magnetization properties of fcc Co
1−
x
Pt
x
(
x⩽0.3) alloy nanowires fabricated by electrodeposition into self-synthesized anodic alumina templates are investigated. Magnetization ...curves, measured for varying wire geometries, show a crossover of easy axis of magnetization from parallel to perpendicular to the nanowire axis as a function of the diameter and length. The measured values of coercivity (
H
c) and remanent squareness (SQ) of CoPt nanowire arrays, as a function of angle (
θ) between the field and wire axis, support the crossover of easy axis of magnetization. The curling mode of the magnetization reversal process is observed for CoPt nanowire arrays. At low temperatures, the easy axis for magnetization of the nanowires is observed to deviate from the room-temperature orientation.
The effort is made to grow the cellular segmentation patterning of undoped and Zr doped Tungsten Oxide (ZWO) coatings engineered by aerosol assisted Chemical Vapor Deposition (AACVD) onto silica ...glass at 400 °C. Nanostructured cauliflowers were successfully grown without using any particular template via the chemical route of AACVD for undoped and Zr doped Tungsten Oxide. The tailored coatings of nano cauliflowers were explored by employing FE-Scanning electron microscopy/Energy Dispersive X-ray spectroscopy (FE-SEM/EDX), X-ray photoelectron spectroscopy (XPS), X-ray diffractometry (XRD), Fourier transformation Infrared spectroscopy (FTIR), UV-VIS spectroscopy (UV-VIS) and four-point probe method to study surface morphological, chemical composition, optical and electrical properties systematically. Morphological features present fractal-type cauliflower patterning because of Zr incorporation. XRD spectra revealed a monoclinic (WO3) phase in undoped Tungsten Oxide with preferential orientation (0 2 0) whereas Zr doping triggered the growth of Magneli suboxide W5O14 with tetragonal (0 0 1) preferred reflection. Adding Zr dopant caused a slight expansion of lattice with a decrease in crystallite size (54–18) nm. Vibrational information exhibits shoulder at around 854.30 cm−1, attributed to O–W–O bond shifting. Undoped and Zr doped Tungsten oxide thin film signatures positioned at 446.65 cm-1, 692 cm-1, and 854.30 cm-1 are witnessed with a red and blue shift in all rest of the Zr doped thin films. The mismatch of W and Zr ions in ionic radii, electronegativity, and thermal coefficients promote stresses leading to the variation in lattice parameters, bond length, and crystallite size with stretching of IR modes attributed to the incorporation of Zr into the host lattice sites of Tungsten oxide. XPS deconvoluted peaks yield the analysis for bond energy of O1s electrons located around 505.19 eV and 510.85 eV characterized as metallic oxide of Tungsten (WO3). UV-VIS spectroscopy presented a highly absorptive nature of coatings in the spectral range between (300–900) nm with the widening of both direct (1.9–3.2) eV and indirect (1.9–2.6) eV band gap which is of absolute interest for both fundamental and applied aspects. Transport properties unveiled the decrease of electrical resistivity of order from 106 Ω-cm (undoped) to 105 Ω-cm (Zr doped), attributed to grown high angle nanoparticles boundaries of tungsten oxide contribute to governing of nano cauliflowers and, as a result, the volume of the grain boundaries increases. The interplay between crystalline quality, tuned architecture, and oxygen vacancies can contribute to the understanding of morphological, optical, and transport properties.
•Fractal type Zr doped tungsten oxide nanostructured cauliflowers produced by AACVD.•Microstructural, optical, and electrical properties were explored systematically.•Transformation from tetragonal preferential orientation (0 0 1) to triclinic tungsten oxide with (0 2 0).•Highly absorptive films observed with band gap widening from 2.6 to 3.0 eV.
▶ The angular distribution of LPP ions from target metals has no systematic correlation with the square-root of atomic mass of the target metals. ▶ The angular distribution of LPP ions exhibits ...systematic dependence on the room temperature Debye–Waller's thermal parameter B or the mean-square amplitude of atomic vibrations 〈u2〉. ▶ The ablation yield (atoms/shot) of target metals under identical irradiation conditions is also a function of the room temperature B-factor or 〈u2〉.
Five metals (Zn, Cu, Ni, Ti, and Mo) were irradiated with 150 shots of a Q-switched Nd:YAG pulsed laser in a vacuum of 10−3torr. The ions projected out of the laser-produced plasma (LPP) plume were detected by CR-39 detectors positioned at −15°, 0°, 30°, 60°, and 90° with respect to the target-surface normal at a distance of 5cm from the target in each case. The angular distribution of LPP ions, which is characterized by the exponent n of cosnθ distribution, is given by n=2.5–11 for the five target metals. The value of the exponent n has no systematic correlation with the square-root of atomic mass of the target metals but exhibits systematic dependence on the room temperature Debye–Waller's thermal parameter B or the mean-square amplitude of atomic vibrations 〈u2〉. Likewise, the ablation yield (atoms/shot) of the twelve target metals investigated by Thestrup et al. (2002) 8 under identical irradiation conditions is a function of the room temperature B-factor or 〈u2〉.
▶ Ni nano particles enhancing SP
2 fraction and thus induces graphitization in the DLC films. ▶ The average rms increases from 7.7
nm to 13.1
nm by Ni incorporation. ▶ Vertically elevated surface ...structures increases and ranges up to 50
nm. ▶ The mean crystallite size of Ni is about 40
nm in the growing DLC films. ▶ The G-band can be tuned by Ni incorporation.
The structure and surface morphology of Ni-incorporated diamond like carbon (Ni:DLC) films have been investigated. These films were deposited on Si substrates using pulsed laser deposition (PLD) technique. A KrF Excimer laser (
λ
=
248 nm) was used for co-ablation from multi component Ni–graphite target. The concentration of Ni was varied by ablating the Ni part of the target with various numbers of laser pulses. The SEM and AFM analysis reveals that the surface is composed of segregates of Ni which increases with the increase in Ni content during the growth process. The structural investigations by XRD and Raman spectroscopy provided information about the orientation of the incorporated constituent and the ordering of the carbon species. Maximum height of the nano structures which were observed on the surface was ∼50
nm. The G-peak of the graphite was shifted towards higher wave number due to enhancement in SP
2 sites which have been increased due to the increase in the Ni concentration. A small change in the surface roughness ranging from 7.78
nm to 13.1
nm due to increased Ni concentration was also observed.
