Structural and magnetic properties of CoFe2O4 thin films deposited by laser ablation on Si (001) substrates

Araujo, Cristiano; Almeida, Bernardo; Aguiar, Micaela Maria Assis; Mendes, J. A.

doi:10.1016/j.vacuum.2008.03.014

Cited by 28 publications

(14 citation statements)

References 10 publications

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“…To the best of our knowledge, the in-plane H c values of 2.5−2.8 kOe observed for α-PLD-grown CFO films ( Table 2) are one of the highest values ever reported for any in situ grown polycrystalline CFO films. Reported H c values vary from 0.2 to 1.2 kOe for as-grown CFO films with one of the highest H c values reported as 7.5 kOe for CFO films grown using rf sputtering process, but requiring ex situ post annealing at 900°C in air for 2 h. [15][16][17][18][19]22,53 To clearly demonstrate the enhanced magnetic properties of α-PLD-grown CFO thin films, we have shown the M−H curves for both α-PLD-and 90°-PLD-deposited CFO films at thicknesses of 100 and 200 nm in panels a and b in Figure 8, respectively. It is worth noting in this figure that there is a kink in the M−H loops near zero field for 90°-PLD-grown CFO films, whereas this feature is absent for α-PLD-grown CFO films.…”

Section: Resultsmentioning

confidence: 99%

Nanocolumnar Interfaces and Enhanced Magnetic Coercivity in Preferentially oriented Cobalt Ferrite Thin Films Grown Using Oblique-Angle Pulsed Laser Deposition

Mukherjee

Hordagoda

Hyde

et al. 2013

ACS Appl. Mater. Interfaces

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Highly textured cobalt ferrite (CFO) thin films were grown on Si (100) substrates using oblique-angle pulsed laser deposition (α-PLD). X-ray diffraction and in-depth strain analysis showed that the obliquely deposited CFO films had both enhanced orientation in the (111) crystal direction as well as tunable compressive strains as a function of the film thicknesses, in contrast to the almost strain-free polycrystalline CFO films grown using normal-incidence PLD under the same conditions. Using in situ optical plume diagnostics the growth parameters in the α-PLD process were optimized to achieve smoother film surfaces with roughness values as low as 1-2 nm as compared to the typical values of 10-12 nm in the normal-incidence PLD grown films. Cross-sectional high resolution transmission electron microscope images revealed nanocolumnar growth of single-crystals of CFO along the (111) crystallographic plane at the film-substrate interface. Magnetic measurements showed larger coercive fields (∼10 times) with similar saturation magnetization in the α-PLD-grown CFO thin films as compared to those deposited using normal-incidence PLD. Such significantly enhanced magnetic coercivity observed in CFO thin films make them ideally suited for magnetic data storage applications. A growth mechanism based on the atomic shadowing effect and strain compression-relaxation mechanism was proposed for the obliquely grown CFO thin films.

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Section: Resultsmentioning

confidence: 99%

Nanocolumnar Interfaces and Enhanced Magnetic Coercivity in Preferentially oriented Cobalt Ferrite Thin Films Grown Using Oblique-Angle Pulsed Laser Deposition

Mukherjee

Hordagoda

Hyde

et al. 2013

ACS Appl. Mater. Interfaces

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“…11 In the above-mentioned applications, spinel was mostly prepared as bulk material using co-precipitation, 4,5 sol-gel freeze-drying, 10 combustion reaction methods [11][12][13][14][15][16] or thermal decomposition. 9 Thin films have been investigated with lesser emphasis using sol-gel, 17 pulsed laser deposition, 18,19 electrochemical deposition 20,21 and atomic layer deposition. 22 In this study we propose the implementation of chemical vapor deposition as a rational preparation method for iron-cobalt spinel thin films to illustrate the interplay between catalytic activity, which is investigated using a model planar catalyst configuration, and composition, site occupation and electrical properties.…”

Section: Introductionmentioning

confidence: 99%

Tailoring the properties and the reactivity of the spinel cobalt oxide

Bahlawane

Ngamou

Vannier

et al. 2009

Phys. Chem. Chem. Phys.

152

119

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Pulsed spray evaporation chemical vapor deposition (PSE-CVD) was employed for the synthesis of cobalt-based spinel oxide thin films, Co(3-x)Fe(x)O4 with x = 0-1.56. XRD, Raman scattering and FTIR emission spectroscopy show that the normal spinel structure was retained for 0 < or = x < or = 0.65 by the selective insertion of Fe3+ in the octahedral sites. The spinel inversion was noticed above this range, whereas the insertion of Fe2+ was first indicated with x > or = 1. The room-temperature electrical resistivity of the thin films was controlled between 9 and 0.007 Omega cm by the adjustment of iron doping concentration. Furthermore an improvement of the thermal stability of the spinel was noticed upon doping by iron. The reducibility of the spinel in the presence of molecular hydrogen was efficiently adjusted by a shift of the reduction temperature by up to 110 degrees C upon the controlled insertion of iron in the octahedral sites of the spinel. The investigation of the catalytic oxidation of CO and ethanol over Co(3-x)Fe(x)O4 films with controlled structural modification enabled the confirmation of the Mars-van Krevelen mechanism for the oxidation of CO and the tight correlation between the selectivity of the conversion of ethanol to acetaldehyde and the abundance of surface basic sites. The controlled iron doping was demonstrated to be an efficient strategy to tune the reactivity and the selectivity of the cobalt-based spinel oxide. The doping-induced transition from normal to inverse spinel was observed to induce a clear discontinuity in the trend of all investigated physicochemical properties.

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“…On account of large magnetocrystalline anisotropy, high coercivity, moderate saturation magnetization, large magnetostrictive coefficient, chemical stability, and mechanical hardness, which generally are helpful for magnetic recording devices, magneto-optical recording, and electronic devices, cobalt ferrites are nowadays highly in demand. Currently, the well-known established techniques used for fabricating the ferrite films include pulsed laser deposition, rf-magnetron sputtering, electron beam evaporation, metal organic chemical vapour deposition, and molecular beam epitaxy [7][8][9][10]. Most of these techniques involve a two step process.…”

Section: Introductionmentioning

confidence: 99%

Cobalt Ferrite Nanocrystallites for Sustainable Hydrogen Production Application

Gaikwad

Chae

Mane

et al. 2011

International Journal of Electrochemistry

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Cobalt ferrite, CoFe 2 O 4 , nanocrystalline films were deposited using electrostatic spray method and explored in sustainable hydrogen production application. Reflection planes in X-ray diffraction pattern confirm CoFe 2 O 4 phase. The surface scanning microscopy photoimages reveal an agglomeration of closely-packed CoFe 2 O 4 nanoflakes. Concentrated solar-panel, a two-step water splitting process, measurement technique was preferred for measuring the hydrogen generation rate. For about 5 hr sustainable, 440 mL/hr, hydrogen production activity was achieved, confirming the efficient use of cobalt ferrite nanocrystallites film in hydrogen production application.

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Structural and magnetic properties of CoFe2O4 thin films deposited by laser ablation on Si (001) substrates

Cited by 28 publications

References 10 publications

Nanocolumnar Interfaces and Enhanced Magnetic Coercivity in Preferentially oriented Cobalt Ferrite Thin Films Grown Using Oblique-Angle Pulsed Laser Deposition

Nanocolumnar Interfaces and Enhanced Magnetic Coercivity in Preferentially oriented Cobalt Ferrite Thin Films Grown Using Oblique-Angle Pulsed Laser Deposition

Tailoring the properties and the reactivity of the spinel cobalt oxide

Cobalt Ferrite Nanocrystallites for Sustainable Hydrogen Production Application

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