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Title: Magnetic properties of Ga doped cobalt ferrite: Compton scattering study

Abstract

We present the spin momentum density of Ga doped CoFe{sub 2}O{sub 4} at 100 K using magnetic Compton scattering. The measurement has been performed using circularly polarized synchrotron radiations of 182.65 keV at SPring8, Japan. The experimental profile is decomposed into its constituent profile to determine the spin moment at individual sites. Co atom has the maximum contribution (about 58%) in the total spin moment of the doped CoFe{sub 2}O{sub 4}.

Authors:
; ;  [1];  [2]; ;  [3]
  1. Department of Physics, University College of Science, M.L. Sukhadia University, Udaipur-313001 (India)
  2. Department of Physics, Manipal University, Jaipur-303007 (India)
  3. Japan Synchrotron Radiation Research Institute, SPring8, 1-1-1 Kouto, Sayo, Hyogo 679-5198 (Japan)
Publication Date:
OSTI Identifier:
22269398
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1591; Journal Issue: 1; Conference: 58. DAE solid state physics symposium 2013, Patiala, Punjab (India), 17-21 Dec 2013; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; COBALT; COBALT OXIDES; COMPTON EFFECT; DENSITY; DOPED MATERIALS; FERRITE; FERRITES; MAGNETIC PROPERTIES; SPIN; SYNCHROTRON RADIATION

Citation Formats

Sharma, Arvind, E-mail: arvind.phd.swm@gmail.com, Mund, H. S., Ahuja, B. L., Sahariya, Jagrati, Itou, M., and Sakurai, Y. Magnetic properties of Ga doped cobalt ferrite: Compton scattering study. United States: N. p., 2014. Web. doi:10.1063/1.4873088.
Sharma, Arvind, E-mail: arvind.phd.swm@gmail.com, Mund, H. S., Ahuja, B. L., Sahariya, Jagrati, Itou, M., & Sakurai, Y. Magnetic properties of Ga doped cobalt ferrite: Compton scattering study. United States. doi:10.1063/1.4873088.
Sharma, Arvind, E-mail: arvind.phd.swm@gmail.com, Mund, H. S., Ahuja, B. L., Sahariya, Jagrati, Itou, M., and Sakurai, Y. 2014. "Magnetic properties of Ga doped cobalt ferrite: Compton scattering study". United States. doi:10.1063/1.4873088.
@article{osti_22269398,
title = {Magnetic properties of Ga doped cobalt ferrite: Compton scattering study},
author = {Sharma, Arvind, E-mail: arvind.phd.swm@gmail.com and Mund, H. S. and Ahuja, B. L. and Sahariya, Jagrati and Itou, M. and Sakurai, Y.},
abstractNote = {We present the spin momentum density of Ga doped CoFe{sub 2}O{sub 4} at 100 K using magnetic Compton scattering. The measurement has been performed using circularly polarized synchrotron radiations of 182.65 keV at SPring8, Japan. The experimental profile is decomposed into its constituent profile to determine the spin moment at individual sites. Co atom has the maximum contribution (about 58%) in the total spin moment of the doped CoFe{sub 2}O{sub 4}.},
doi = {10.1063/1.4873088},
journal = {AIP Conference Proceedings},
number = 1,
volume = 1591,
place = {United States},
year = 2014,
month = 4
}
  • The magnetic Compton scattering of a Tb{sub 32}Fe{sub 55}O{sub 13} film was measured in order to investigate the microscopic magnetization processes (i.e., the spin moment, orbital moment, and element specific moments). The trend of the spin magnetic moment was the same as that of the total magnetic moment but opposite to the orbital magnetic moment. In the low magnetic field region, the magnetic moments were not perfectly aligned perpendicular to the film surface, and the perpendicular components were found to mainly arise from the magnetic moment of Tb. Oxygen atoms hinder long range magnetic interaction and hence also affect themore » magnetization process of the magnetic moments of Tb and Fe.« less
  • We have studied spin dependent electron momentum density in CoGa{sub 0.3}Fe{sub 1.7}O{sub 4} at 300 K using magnetic Compton spectroscopy. It is observed that major contribution to total spin moment mainly arises from Co ions while itinerant electrons show negative polarization. Orbital contribution has been deduced by comparing the magnetic Compton spectroscopy with the magnetization data. It is revealed that the anisotropy in magnetization in the system increases with the Ga doping.
  • The influence of cation composition on the magnitude of perpendicular anisotropy and the shape of the hysteresis loop of polycrystalline films of Co/sub x/Fe/sub 3-x/O/sub 4/ has been studied. Dispersion dependences of the Faraday effect and the coefficients of optical absorption and of the magnetooptical figure of merit are also investigated. The films were produced by vacuum evaporation of a mixture of Co and Fe with a specified component ratio on to substrates of cover glass and fused silica, followed by annealing of the deposited condensate in an atmosphere with controlled oxygen content. The films were polycrystals having a spinelmore » structure, with crystallite size 400-500 /angstrom/. The thickness of the films was /approx/ 2000 /angstrom/. The cation composition of the films was determined by means of x-ray fluorescence analysis. The samples produced exhibited perpendicular magnetic anisotropy.« less
  • Nanoscale ferrimagnetic particles have a diverse range of uses from directed cancer therapy and drug delivery systems to magnetic recording media and transducers. Such applications require the production of monodisperse nanoparticles with well-controlled size, composition, and magnetic properties. To fabricate these materials purely using synthetic methods is costly in both environmental and economical terms. However, metal-reducing microorganisms offer an untapped resource to produce these materials. Here, the Fe(III)-reducing bacterium Geobacter sulfurreducens is used to synthesize magnetic iron oxide nanoparticles. A combination of electron microscopy, soft X-ray spectroscopy, and magnetometry techniques was employed to show that this method of biosynthesis resultsmore » in high yields of crystalline nanoparticles with a narrow size distribution and magnetic properties equal to the best chemically synthesized materials. In particular, it is demonstrated here that cobalt ferrite (CoFe{sub 2}O{sub 4}) nanoparticles with low temperature coercivity approaching 8 kOe and an effective anisotropy constant of {approx} 10{sup 6} erg cm{sup -3} can be manufactured through this biotechnological route. The dramatic enhancement in the magnetic properties of the nanoparticles by the introduction of high quantities of Co into the spinel structure represents a significant advance over previous biomineralization studies in this area using magnetotactic bacteria. The successful production of nanoparticulate ferrites achieved in this study at high yields could open up the way for the scaled-up industrial manufacture of nanoparticles using environmentally benign methodologies. Production of ferromagnetic nanoparticles for pioneering cancer therapy, drug delivery, chemical sensors, catalytic activity, photoconductive materials, as well as more traditional uses in data storage embodies a large area of inorganic synthesis research. In particular, the addition of transition metals other than Fe into the structure of magnetite (Fe{sub 3}O{sub 4}) has been shown to greatly enhance the magnetic properties of the particles, tailoring them to different commercial uses. However, synthesis of magnetic nanoparticles is often carried out at high temperatures with toxic solvents resulting in high environmental and energy costs. Additionally, these ferrite nanoparticles are not intrinsically biocompatible, and to make them suitable for insertion into the human body is a rather intricate task. A relatively unexplored resource for magnetic nanomaterial production is subsurface Fe(III)-reducing bacteria, as these microorganisms are capable of producing large quantities of nanoscale magnetite (Fe{sub 3}O{sub 4}) at ambient temperatures. Metal-reducing bacteria live in environments deficient in oxygen and conserve energy for growth through the oxidation of hydrogen or organic electron donors, coupled to the reduction of oxidized metals such as Fe(III)-bearing minerals. This can result in the formation of magnetite via the extracellular reduction of amorphous Fe(III)-oxyhydroxides causing the release of soluble Fe(II) and resulting in complete recrystallization of the amorphous mineral into a new phase. Some previous studies have reported altering the composition of biogenic magnetite produced by Fe(III)-reducing bacteria for industrial and environmental applications. However, research into the commercial exploitation of bacteria to form magnetic minerals has focused primarily on magnetotactic bacteria which form magnetosomal magnetite internally using very different pathways to those bacteria forming magnetite outside the cell. Magnetotactic bacteria live at the sediment-water interface and use internal nanomagnets to guide them to their preferred environmental niche using the Earth's magnetic field. Since magnetotactic bacteria generally grow optimally under carefully controlled microaerobic conditions, the culturing processes for these organisms are challenging and result in low yields of nanomagnetite. Despite these limitations, magnetotactic bacteria have been shown to incorporate {approx}1% Co into the magnetite structure in vivo, and CoFe{sub 2}O{sub 4} was synthesized in vitro, altering the magnetic properties of the material formed. Although these previous studies are an important first step, in order to obtain the degree of control over the magnetic properties required by potential applications, Co must be incorporated into the spinel structure together with high nanoparticle yields. It is not clear at present how this could be achieved using the highly regulated intracellular magnetosome systems. We present an alternative and efficient method to produce large quantities of highly crystalline magnetite and cobalt ferrite nanoparticles using the Fe(III)-reducing bacterium, Geobacter sulfurreducens, at ambient temperatures through the extracellular dissimilatory reduction of Fe(III)-oxyhydroxides without and with addition of cobalt.« less
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