scholarly journals Room temperature spin filtering in epitaxial cobalt-ferrite tunnel barriers

2007 ◽  
Vol 91 (12) ◽  
pp. 122107 ◽  
Author(s):  
A. V. Ramos ◽  
M.-J. Guittet ◽  
J.-B. Moussy ◽  
R. Mattana ◽  
C. Deranlot ◽  
...  
Keyword(s):  
Room Temperature ◽  
Cobalt Ferrite ◽  
Tunnel Barriers ◽  
Spin Filtering

Design optimization and stability enhancement of modified inter-digital capacitive humidity transducer with cobalt ferrite nanoparticles as dielectric

2019 ◽  
Vol 42 (4) ◽  
pp. 917-923
Author(s):  
Jiss Paul ◽  
Jacob Philip
Keyword(s):  
Recovery Time ◽  
Room Temperature ◽  
Cobalt Ferrite ◽  
Dynamic Range ◽  
Ferrite Nanoparticles ◽  
Sensitive Layer ◽  
Humidity Transducer ◽  
The Stability ◽  
Stability Enhancement ◽  
Sensing Characteristics

A modified inter-digital capacitive (IDC) transducer for relative humidity (RH) measurement is fabricated by coating a thick film of polyvinyl alcohol (PVA) on the structure. The effective capacitance of the sensor, measured at 1MHz, increases with RH at room temperature. The RH sensing characteristics of PVA coated IDC transducer are analysed in terms of its sensitivity, dynamic range, frequency response, repeatability and recovery time. It is found that the stability of such a PVA based RH transducer improves remarkably by diffusing nanoparticles of CoFe2O4 in the PVA layer. A standard deviation of ± 0.05 and ± 0.01 for a sensitive layer with pure PVA and PVA-CoFe2O4 combination respectively results in a measurement error of ± 0.005 and ± 0.003.

scholarly journals Chemical Solution Deposition of Ordered 2D Arrays of Room-Temperature Ferrimagnetic Cobalt Ferrite Nanodots

Polymers ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1598 ◽  
Author(s):  
Jin Xu ◽  
Justin Varghese ◽  
Giuseppe Portale ◽  
Alessandro Longo ◽  
Jamo Momand ◽  
...  
Keyword(s):  
Chemical Solution Deposition ◽  
Room Temperature ◽  
Cobalt Ferrite ◽  
Magnetic Nanostructures ◽  
Memory Storage ◽  
Blocking Temperature ◽  
Chemical Solution ◽  
Solution Deposition ◽  
X Ray ◽  
2D Arrays

Over the past decades, the development of nano-scale electronic devices and high-density memory storage media has raised the demand for low-cost fabrication methods of two-dimensional (2D) arrays of magnetic nanostructures. Here, we present a chemical solution deposition methodology to produce 2D arrays of cobalt ferrite (CFO) nanodots on Si substrates. Using thin films of four different self-assembled block copolymers as templates, ordered arrays of nanodots with four different characteristic dimensions were fabricated. The dot sizes and their long-range arrangement were studied with scanning electron microscopy (SEM) and grazing incident small-angle X-ray scattering (GISAXS). The structural evolution during UV/ozone treatment and the following thermal annealing was investigated through monitoring the atomic arrangement with X-ray absorption fine structure spectroscopy (EXAFS) and checking the morphology at each preparation step. The preparation method presented here obtains array types that exhibit thicknesses less than 10 nm and blocking temperatures above room temperature (e.g., 312 K for 20 nm diameter dots). Control over the average dot size allows observing an increase of the blocking temperature with increasing dot diameter. The nanodots present promising properties for room temperature data storage, especially if a better control over their size distribution will be achieved in the future.

SYNTHESIS AND CHARACTERIZATION OF BIFUNCTIONAL CoFe2O4–ZnS NANOCOMPOSITE

2011 ◽  
Vol 10 (01n02) ◽  
pp. 237-240 ◽  
Author(s):  
J. P. BORAH ◽  
C. BORGOHAIN ◽  
K. C. SARMA ◽  
K. K. SENAPATI ◽  
P. PHUKAN
Keyword(s):  
Drug Targeting ◽  
Room Temperature ◽  
Cobalt Ferrite ◽  
Magnetic Nanomaterials ◽  
X Ray Diffraction ◽  
Chemical Route ◽  
Magnetic Fluid Hyperthermia ◽  
X Ray ◽  
Transmission Electron

The synthesis of composite magnetic nanomaterials has received increasing attention due to their electronic, magnetic, catalytic, and chemical or biological sensing properties. We have prepared cobalt ferrite–zinc sulfide nanocomposites by a chemical route. The synthesized nanocomposites were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), and photoluminescence spectrometer (PL). The fluorescent magnetic nanoparticles (FMNPs) had a typical diameter of 30±5 nm and saturation magnetization of 5.8 emu g-1 at room temperature. So, these FMNPs may be potentially applied in different fields such as optoelectronic devices, biolabeling, imaging, drug targeting, bioseparation, magnetic fluid hyperthermia, etc.

Preparation of Ferromagnetic Manganese Doped Cobalt Ferrite-Silica Core Shell Nanoparticles for Possible Biological Application

2013 ◽  
Vol 334-335 ◽  
pp. 19-25 ◽  
Author(s):  
S. Rostamzadehmansoor ◽  
Mirabdullah Seyed Sadjadi ◽  
K. Zare ◽  
Nazanin Farhadyar
Keyword(s):  
Magnetic Properties ◽  
Room Temperature ◽  
Cobalt Ferrite ◽  
Biomedical Application ◽  
Strong Dependence ◽  
Precipitation Method ◽  
Cell Protein ◽  
Core Shell ◽  
X Ray ◽  
Cell Parameters

Magnetic oxide nanoparticles with proper surface coatings are increasingly being evaluated for clinical applications such as hyperthermia, drug delivery, magnetic resonance imaging, transfection and cell/protein separations. In this work, we investigated synthesis, magnetic properties of silica coated metal ferrite, (CoFe2O4)/SiO2 and manganese doped cobalt ferrite nanoparticles (Mnx-Co1-xFe2O4 with x = 0.02, 0.04 and 0.06)/SiO2 for possible biomedical application. All the ferrites nanoparticles were prepared by co-precipitation method using FeCl3.6H2O, CoCl2.6H2O and MnCl2.2H2O as precursors, and were silica coated by the Stober process in directly ethanol. The composition, phase structure and morphology of the prepared core/shell cobalt ferrites nanostructures were characterized by powder X-ray diffraction (XRD), Fourier Transform infra-red spectra (FTIR), Field Emission Scanning Electron Microscopy and energy dispersive X-ray analysis (FESEM-EDAX). The results revealed that all the samples maintain the ferrite spinel structure. While, the cell parameters decrease monotonically by increase of Mn content indicating that the Mn ions are substituted into the lattice of CoFe2O4. The magnetic properties of the prepared samples were investigated at room temperature using Vibrating Sample Magnetometer (VSM). The results revealed a strong dependence of room temperature magnetic properties on (1) doping content, x; (2) particle size and ion distributions.

scholarly journals Tunnel Contacts for Spin Injection into Silicon: The Si-Co Interface with and without a MgO Tunnel Barrier—A Study by High-Resolution Rutherford Backscattering

2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
S. P. Dash ◽  
D. Goll ◽  
P. Kopold ◽  
H. D. Carstanjen
Keyword(s):  
High Resolution ◽  
Room Temperature ◽  
Spin Injection ◽  
Schottky Contact ◽  
Tunnel Barrier ◽  
Si Substrate ◽  
High Crystalline Quality ◽  
Tunnel Barriers ◽  
Interface Structures

In order to obtain high spin injection efficiency, a ferromagnet-semiconducor Schottky contact must be of high crystalline quality. This is particularly important in the case of ferromagnet-silicon interfaces, since these elements tend to mix and form silicides. In this study Co-Si (100) interfaces were prepared in three different ways: by evaporation at room temperature, low temperature (), and with Sb as surfactant, and their interface structures were analyzed by high-resolution RBS (HRBS). In all cases more or less strong in-diffusion of Co with subsequent silicide formation was observed. In order to prevent the mixing of Co and Si, ultra thin MgO tunnel barriers were introduced in-between them. In situ HRBS characterization confirms that the MgO films were very uniform and prevented the mixing of the Si substrate with deposited Co and Fe films effectively, even at .

Effect of Zinc Oxide Nanocrystals in Media Containing E. coli and C. xerosis Bacteria

2005 ◽  
Vol 900 ◽  
Author(s):  
Triana Merced ◽  
Stephanie Santos ◽  
Omayra Rivera ◽  
Nicole Villalba ◽  
Yahira Baez ◽  
...  
Keyword(s):  
Zinc Oxide ◽  
Room Temperature ◽  
Cobalt Ferrite ◽  
Growth Curves ◽  
Adaptation Period ◽  
E Coli ◽  
Standard Curve ◽  
Stable Suspension ◽  
Zno Nanocrystals ◽  
Doped Zno

ABSTRACTThe present investigation is centered on the study of the growth curves of E. coli and C. xerosis bacteria in the presence of nanosize particles of Zinc Oxide. Previous works demonstrated the sensitivity of the bacteria, when these were reproduced in media that contain nanoparticles of luminescent silicon and Cobalt Ferrite. Doped ZnO nanocrystals were synthesized by conventional precipitation in ethanol solutions as reported by Spanhel and Anderson for bare ZnO. In our case, the syntheses were carried out under room-temperature conditions.The experimental results of E. coli bacteria in contact with a stable suspension of nanoparticles of Zinc Oxide, shows a growth curve without adaptation period. Moreover a short and slowly logarithmic stage has been observed, reaching the stationary stage after approximately four hours compared with one in absence of the nanoparticles (standard curve). During the observations, a change in the lifetime of the bacteria (metabolism) with particulate was noticed,as well as the beginning of the mortality stage. However, different results were recorded for silicon and ferrite. For the case of the bacteria C. xerosis, the curve with particles is above its standard curve, for all times with none of the oscillations which occured in the nanometer silicon. For these bacteria the beginning of the mortality stage is observed when they have particles. For both bacteria with Zinc Oxide nanoparticles this occurs approximately after nine hours.

Spin-Polarized Current in Spin Valves and Magnetic Tunnel Junctions

MRS Bulletin ◽  
2006 ◽  
Vol 31 (5) ◽  
pp. 389-394 ◽  
Author(s):  
Stuart Parkin
Keyword(s):  
Room Temperature ◽  
Tunnel Junctions ◽  
Magnetic Tunnel Junctions ◽  
Memory Storage ◽  
Tunnel Barrier ◽  
Tunnel Magnetoresistance ◽  
Ferromagnetic Electrodes ◽  
Diffusive Scattering ◽  
Spin Polarized ◽  
Tunnel Barriers

AbstractSpin-polarized currents can be generated by spin-dependent diffusive scattering in magnetic thin-film structures or by spin-dependent tunneling across ultrathin dielectrics sandwiched between magnetic electrodes.By manipulating the magnetic moments of the magnetic components of these spintronic materials, their resistance can be significantly changed, allowing the development of highly sensitive magnetic-field detectors or advanced magnetic memory storage elements.Whereas the magneto-resistance of useful devices based on spin-dependent diffusive scattering has hardly changed since its discovery nearly two decades ago, in the past five years there has been a remarkably rapid development in both the basic understanding of spin-dependent tunneling and the magnitude of useful tunnel magnetoresistance values.In particular, it is now evident that the magnitude of the spin polarization of tunneling currents in magnetic tunnel junctions not only is related to the spin-dependent electronic structure of the ferromagnetic electrodes but also is considerably influenced by the properties of the tunnel barrier and its interfaces with the magnetic electrodes.Whereas the maximum tunnel magnetoresistance of devices using amorphous alumina tunnel barriers and 3d transition-metal alloy ferromagnetic electrodes is about 70% at room temperature, using crystalline MgO tunnel barriers in otherwise the same structures gives tunnel magnetoresistance values of more than 350% at room temperature.

Magnons and Phonons in Cobalt Ferrite

1974 ◽  
Vol 52 (5) ◽  
pp. 396-398 ◽  
Author(s):  
H. C. Teh ◽  
M. F. Collins ◽  
H. A. Mook
Keyword(s):  
Acoustic Phonon ◽  
Room Temperature ◽  
Cobalt Ferrite ◽  
Zone Boundary ◽  
Phonon Branch ◽  
Longitudinal Acoustic ◽  
Transverse Acoustic ◽  
Low Energies ◽  
Longitudinal Acoustic Phonon ◽  
Infrared Data

Magnons and phonons have been observed in a single crystal of cobalt ferrite, CoFe2O1 at room temperature. Dispersion relations are plotted for the [001] and the [111] directions. The longitudinal acoustic phonon branch has been measured out to the zone boundary in both directions, while the transverse acoustic branch has been completely determined only in the [001] direction. The acoustic magnon branches are well defined at low energies, but they rapidly lose intensity and disappear at around 9 THz. We have not determined uniquely why this happens, but some possibilities are given. Optic branches have been observed at around 11.3 and 14.0 THz. Infrared data indicate that the first branch is probably of phonon character and the second of magnon character.

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